The present invention relates to the use of certain resorcinol derivatives as skin lightening agents.
The terms xe2x80x9clightening agentxe2x80x9d and xe2x80x9cdepigmentation agentxe2x80x9d are used interchangeably throughout this document.
Skin color in humans arises from a complex series of cellular processes that are carried out within a unique population of cells called melanocytes. Melanocytes are located in the lower part of the epidermis, and their function is to synthesize a pigment, melanin, which protects the body from the damaging effects of ultraviolet radiation.
When skin is exposed to ultraviolet radiation, such as that contained in sunlight, melanocytes increase their synthesis of melanin. Melanin is deposited in melanosomes, which are vesicles found within the cell. The melanosomes are extruded from the cell and carried to the surface of the skin by keratinocytes, which internalize the melanin-containing melanosomes. The end result is that the visible layers of the skin exhibit a brown color typically known as a xe2x80x9ctanxe2x80x9d. The darkness of the color observed in the skin is proportionate to the amount of melanin synthesized by melanocytes and transferred to the keratinocytes.
The mechanism by which skin pigmentation is formed, melanogenesis, is particularly complex and schematically involves the following main steps: Tyrosinexe2x86x92L-Dopaxe2x86x92Dopaquinonexe2x86x92Dopachromexe2x86x92Melanins. The first two reactions in this series are catalyzed by the enzyme tyrosinase. The activity of tyrosinase is promoted by the action of xcex1-melanocyte stimulating hormone or UV rays to have melanin eventually formed as chromatism in the skin. It is well established that a substance has a depigmenting effect if it acts directly on the vitality of the epidermal melanocytes where melanogenesis normally occurs and/or if it interferes with one of the stages in melanin biosynthesis. The active compounds that are employed in the various methods and compositions of this invention inhibit tyrosinase and thus inhibit or decrease melanin biosynthesis.
There is a strong demand for agents that enable acquired deposition sites, such as spots or freckles, to be restored to a normal skin color. For this purpose, a variety of agents and methods have been developed and put on the market. Examples of such methods are (a) a method wherein vitamin C (L-ascorbic acid) having good reducing ability is administered orally in large amounts, (b) a method wherein glutathione is administered parenterally; (c) a method wherein a peroxide, such as hydrogen peroxide, zinc peroxide, sodium peroxide and the like, which is believed to have the bleaching action of melamine, is administered: and (d) a method wherein vitamin C or cysteine is administered topically in the form of an ointment, cream, lotion or the like. Vitamin C has a problem with respect to stability and becomes so unstable in water-containing systems that they will cause changes in odor and color. Thiol compounds such as glutathione and cysteine do not exhibit a satisfactory depigmental effect since the development of the effect is very slow.
The substances in widest use at the present time as depigmentors are, in particular, hydroquinone and its derivatives, particularly its ethers such as hydroquinone monomethyl ether. These compounds, while effective, are known to produce side effects that can be dangerous. Hydroquinone, use of which is limited to a concentration of 2%, is both irritating and cytotoxic to the melanocyte.
U.S. Pat. No. 4,526,179 refers to certain hydroquinone fatty esters that have good activity and are less irritating and more stable than hydroquinone.
Japanese Patent Application No. 27909/86 refers to other hydroquinone derivatives that do not have the drawbacks of hydroquinone but that have relatively poor efficacy.
U.S. Pat. No. 5,449,518 refers to 2,5-dihydoxyphenyl carboxylic acid derivatives as skin depigmentation agents.
European Patent Application EP 341,664A1 refers to certain resorcinol derivatives as tyrosinase inhibitors and skin depigmentation agents.
PCT International Publication WO 99/15148 refers to certain resorcinol derivatives as tyrosinase inhibitors and skin depigmentation agents.
The use of topical depigmention agents that have good efficacy and are harmless is particularly desirable for treating the following: regional hyperpigmentation caused by melanocytic hyperactivity, such as idiopathic melasma occurring either during pregnancy (mask of pregnancy or chloasma) or secondary to estrogen-progesterone contraception; local hyperpigmentation caused by benign melanocytic hyperactivity and proliferation such as lentigo senilis or liver spots; accidental hyperpigmentation such as post-lesional photosensitization and scarring; and certain forms of leukoderma such as vitiligo where, if the injured skin cannot be repigmented, the residual zones of normal skin are depigmented to impart a homogeneous white color to the entire skin.
The resorcinol derivatives of formula I, which are defined below and used in the various methods and compositions of this invention, are useful in the treatment of the foregoing dermatological conditions as well as other dermatological conditions, some of which are referred to later in this document, for which the subject being treated desires, for medicinal or cosmetic purposes, to lighten or reduce the pigmentation of the skin affected by the condition.
The resorcinol derivatives of formula I are also useful for the treatment of inflammatory disorders such as psoriasis, dermatitis and acne, and for the treatment of dandruff.
The invention thus provides a compound of formula l: 
or a pharmaceutically acceptable salt thereof, wherein:
R1 is a (C3-C8)cycloalkyl ring or (C5-C8)cycloalkenyl ring, wherein either the cycloalkyl ring or cycloalkenyl ring is substituted by one to three substituents independently selected from the group consisting of cyano; halo; (C1-C6)alkyl; aryl; (C2-C9)heterocycloalkyl; (C2-C9)heteroaryl; aryl(C1-C6)alkyl-; xe2x95x90O; xe2x95x90CHO(C1-C6)alkyl; amino; hydroxy; (C1-C6)alkoxy; aryl(C1-C6)alkoxy-; (C1-C6)acyl; (C1-C6)alkylamino-; aryl(C1-C6)alkylamino-; amino(C1-C6)alkyl-; (C1-C6)alkoxy-COxe2x80x94NHxe2x80x94; (C1-C6)alkylamino-COxe2x80x94; (C2-C6)alkenyl; (C2-C6)alkynyl; hydroxy(C1-C6)alkyl-; (C1-C6)alkoxy(C1-C6)alkyl-; (C1-C6)acyloxy(C1-C6)alkyl-; nitro; cyano(C1-C6)alkyl-; halo(C1-C6)alkyl-; nitro(C1-C6)alkyl-; trifluoromethyl; trifluoromethyl(C1-C6)alkyl-; (C1-C6)acylamino-; (C1-C6)acylamino(C1-C6)alkyl-; (C1-C6)alkoxy(C1-C6)acylamino-; amino(C1-C6)acyl-; amino(C1-C6)acyl(C1-C6)alkyl-; (C1-C6)alkylamino(C1-C6)acyl-; ((C1-C6) alkyl)2amino(C1-C6)acyl-; xe2x80x94CO2R2; xe2x80x94(C1-C6)alkyl-CO2R2; xe2x80x94C(O)N(R2)2; xe2x80x94(C1-C6)alkyl-C(O)N(R2)2; R2ONxe2x95x90; R2ONxe2x95x90(C1-C6)alkyl-; R2ONxe2x95x90CR2(C1-C6)alkyl-; xe2x80x94NR2(OR2); xe2x80x94(C1-C6)alkyl-NR2(OR2); xe2x80x94C(O)(NR2R2); xe2x80x94(C1-C6)alkyl-C(O)(NR2OR2); xe2x80x94S(O)mR2; wherein each R2 is independently selected from hydrogen, (C1-C6)alkyl, aryl, or aryl(C1-C6)alkyl-; R3C(O)Oxe2x80x94, wherein R3 is (C1-C6)alkyl, aryl, or aryl(C1-C6)alkyl-; R3C(O)Oxe2x80x94(C1-C6)alkyl-; R4R5Nxe2x80x94C(O)xe2x80x94Oxe2x80x94; R4R5NS(O)2xe2x80x94; R4R5NS(O)2(C1-C6)alkyl-; R4S(O)2R5Nxe2x80x94; R4S(O)2R5N(C1-C6)alkyl-; wherein m is 0, 1 or 2, and R4 and R5 are each independently selected from hydrogen or (C1-C6)alkyl; xe2x80x94C(xe2x95x90NR6)(N(R4)2); or xe2x80x94(C1-C6)alkyl-C(xe2x95x90NR6)(N(R4)2) wherein R6 represents OR2 or R2 wherein R2 is defined as above;
with the proviso that the cycloalkenyl ring is not aromatic;
with the proviso that R1 must be substituted by at least one of R3C(O)Oxe2x80x94, R3C(O)Oxe2x80x94(C1-C6)alkyl-, R2ONxe2x95x90, R2ONxe2x95x90(C1-C6)alkyl-, R2 ONxe2x95x90CR2(C1-C6)alkyl-, xe2x80x94NR2(OR2), R4R5NS(O)2xe2x80x94, R4R5NS(O)2(C1-C6)alkyl-, R4S(O)2R5Nxe2x80x94, or R4S(O)2R5N(C1-C6)alkyl-;
with the proviso that when R1 is only substituted by one of R2ONxe2x95x90, then R2 cannot be hydrogen.
Where R1 is a cyclohexyl or cyclohexenyl ring, the ring is preferably substituted at the 3- or 4-position, and more preferably at the 4-position.
Where R1 is a cyclopentyl or cyclopentenyl ring, the ring is preferably substituted at the 3-position.
In a preferred embodiment, R1 is monosubstituted.
In a further preferred embodiment, R1 is disubstituted.
In a preferred embodiment, R1 is substituted by at least one of R3C(O)Oxe2x80x94 or R3C(O)Oxe2x80x94(C1-C6)alkyl-.
In a further preferred embodiment, R1 is substituted by at least one of R3C(O)Oxe2x80x94.
In a further preferred embodiment, R1 is substituted by at least one of R3C(O)Oxe2x80x94(C1-6)alkyl-.
In a further preferred embodiment, R1 is substituted by at least one of R2 ONxe2x95x90, R2ONxe2x95x90(C1-C6)alkyl-, or R2ONxe2x95x90CR2(C1-C6)alkyl-; with the proviso that when R1 is only substituted by one of R2ONxe2x95x90, then R2 cannot be hydrogen.
In a further preferred embodiment, R1 is substituted by at least one of R2ONxe2x95x90, with the proviso that when R1 is only substituted by one of R2ONxe2x95x90, then R2 cannot be hydrogen.
In a further preferred embodiment, R1 is substituted by at least one of xe2x80x94NR2(OR2).
In a further preferred embodiment, R1 is substituted by at least one of R4R5NS(O)2xe2x80x94, R4R5NS(O)2(C1-C6)alkyl-, R4S(O)2R5Nxe2x80x94, or R4S(O)2R5N(C1-C6)alkyl-.
In a further preferred embodiment, R1 is substituted by at least one of R4S(O)2R5Nxe2x80x94.
In a further preferred embodiment, R1 is substituted by at least one of R4S(O)2R5N(C1-C6)alkyl-.
In a further preferred embodiment, R1 is a (C3-C8)cycloalkyl ring or (C5-C8)cycloalkenyl ring, wherein either the cycloalkyl ring or cycloalkenyl ring is substituted by one of R3C(O)Oxe2x80x94, R3C(O)Oxe2x80x94(C1-C6)alkyl-, R2ONxe2x95x90, R2ONxe2x95x90(C1-C6)alkyl-, R2ONxe2x95x90CR2(C1-C6)alkyl-, xe2x80x94NR2(OR2), R4R5NS(O)2xe2x80x94, R4R5NS(O)2(C1-C6)alkyl-, R4S(O)2R5Nxe2x80x94, or R4S(O)2R5N(C1-C6)alkyl-; wherein R2, R3, R4 and R5 are as defined above;
with the proviso that the cycloalkenyl ring is not aromatic;
and with the proviso that when R1 is substituted by R2ONxe2x95x90, then R2 cannot be hydrogen.
In a further preferred embodiment, R1 is a (C3-C8)cycloalkyl ring or (C5-C8)cycloalkenyl ring, wherein either the cycloalkyl ring or cycloalkenyl ring is substituted by one of R3C(O)Oxe2x80x94, R3C(O)Oxe2x80x94(C1-C6)alkyl-, R2ONxe2x95x90, or R4S(O)2R5Nxe2x80x94; wherein R2, R3, R4 and R5 are as defined above;
with the proviso that the cycloalkenyl ring is not aromatic;
and with the proviso that when R1 is substituted by R2ONxe2x95x90, then R2 cannot be hydrogen.
In a further preferred embodiment, R1 is substituted by R3C(O)Oxe2x80x94 or R3C(O)Oxe2x80x94(C1-C6)alkyl-.
In a further preferred embodiment, R1 is substituted by R3C(O)Oxe2x80x94.
In a further preferred embodiment, R1 is substituted by R3C(O)Oxe2x80x94(C1-C6)alkyl-.
In a further preferred embodiment, R1 is substituted by R2ONxe2x95x90, R2ONxe2x95x90(C1-C6)alkyl-, or R2ONxe2x95x90CR2(C1-C6)alkyl-, with the proviso that when R1 is substituted by R2ONxe2x95x90, then R2 cannot be hydrogen.
In a further preferred embodiment, R1 is substituted by R2ONxe2x95x90, where R2 cannot be hydrogen.
In a further preferred embodiment, R1 is substituted by xe2x80x94NR2(OR2).
In a further preferred embodiment, R1 is substituted by R4R5NS(O)2xe2x80x94, R4R5NS(O)2(C1-C6)alkyl-, R4S(O)2R5Nxe2x80x94 or R4S(O)2R5N(C1-C6)alkyl-.
In a further preferred embodiment, R1 is substituted by R4S(O)2R5Nxe2x80x94.
In a further preferred embodiment, R1 is substituted by R4S(O)2R5N(C1-C6) alkyl-.
The (C2-C9)heterocycloalkyl substituent, when present on R1, is preferably a group of the formula: 
wherein m is as defined above, and
Z is CH2, NR2, OS, SO, or SO2.
For any of the aforementioned compounds of the present invention, R1 is preferably a group of the formula: 
which is substituted as described above for R1;
wherein n is 0, 1, or 2;
wherein the dashed line indicates an optional double bond at that position.
In a preferred embodiment, n is 0 or 1.
In a further preferred embodiment, n is 0; and the dashed line represents a double bond at that position.
In a further preferred embodiment, n is 1.
In a further preferred embodiment, R1 is substituted by xe2x95x90O, xe2x95x90NOH, CH2OH, 
or a combination thereof.
In a further preferred embodiment, n is 0; R1 is substituted by xe2x95x90NOH; and the dashed line represents a double bond at that position.
In further preferred embodiment, n is 1; and R1 is substituted by xe2x95x90O, xe2x95x90NOH, CH2OH, or 
or a combination thereof.
The invention further provides a compound selected from the group consisting of:
O-Benzyl-4-(2,4-dihydroxyphenyl)cyclohexanone oxime;
(xc2x1)-N-[3-(2,4-Dihydroxyphenyl)cyclohexyl]methanesulfonamide;
(xc2x1)-O-Methyl-3-(2,4-dihydroxyphenyl)cyclohexanone oxime;
(xc2x1)-O-Benzyl-3-(2,4-dihydroxyphenyl)cyclohexanone oxime;
and a pharmaceutically acceptable salt thereof.
The invention further provides a compound selected from the group consisting of:
O-Methyl-4-(2,4-dihydroxyphenyl)cyclohexanone oxime;
(xc2x1)-4-[3-(Hydroxyamino)cyclohexyl]-1,3-benzenediol;
cis-N-[4-(2,4-Dihydroxyphenyl)cyclohexyl]-1-butanesulfonamide;
trans-N-[4-(2,4-Dihydroxyphenyl)cyclohexyl]methanesulfonamide;
cis-N-[4-(2,4-Dihydroxyphenyl)cyclohexyl]methanesulfonamide;
trans-4-(2,4-Dihydroxyphenyl)cyclohexyl) 4-(dimethylamino)benzoate;
trans-4-(2,4-Dihydroxyphenyl)cyclohexyl 4-tert-butyl benzoate;
trans-4-(2,4-Dihydroxyphenyl)cyclohexyl 4-fluorobenzoate;
trans-4-(2,4-Dihydroxyphenyl)cyclohexyl 4-trifluoromethylbenzoate;
trans-4-(2,4-Dihydroxyphenyl)cyclohexyl 4-methoxybenzoate;
trans-4-(2,4-Dihydroxyphenyl)cyclohexyl 4-methylbenzoate;
trans-4-(2,4-Dihydroxyphenyl)cyclohexyl 4-chlorobenzoate;
trans-4-(2,4-Dihydroxyphenyl)cyclohexyl 3,4-dimethylbenzoate;
trans-4-(2,4-Dihydroxyphenyl)cyclohexyl 3,4-dichlorobenzoate;
[4-(2,4-Dihydroxyphenyl)cyclohexyl]methyl propionate;
cis/trans-4-[4-(hydroxyamino)cyclohexyl]-1,3-benzenediol;
trans-4-[4-(methoxyamino)cyclohexyl]-1,3-benzenediol;
and a pharmaceutically acceptable salt thereof.
The present invention further provides a topical pharmaceutical composition for lightening skin or reducing the pigmentation of skin in a human, comprising a pharmaceutically acceptable carrier, and a skin-lightening or pigmentation-reducing amount of a compound of formula I: 
or a pharmaceutically acceptable salt thereof, wherein:
R1 is a (C3-C8)cycloalkyl ring or (C5-C8)cycloalkenyl ring, wherein either the cycloalkyl ring or cycloalkenyl ring is substituted by one to three substituents independently selected from the group consisting of cyano; halo; (C1-C6)alkyl; aryl; (C2-C9)heterocycloalkyl; (C2-C9)heteroaryl; aryl(C1-C6)alkyl-; xe2x95x90O; xe2x95x90CHO(C1-C6)alkyl; amino; hydroxy; (C1-C6)alkoxy; aryl(C1-C6)alkoxy-; (C1-C6)acyl; (C1-C6)alkylamino-; aryl(C1-C6)alkylamino-; amino(C1-C6)alkyl-; (C1-C6)alkoxy-COxe2x80x94NHxe2x80x94; (C1-C6)alkylamino-COxe2x80x94; (C2-C6)alkenyl; (C2-C6)alkynyl; hydroxy(C1-C6)alkyl-; (C1-C6)alkoxy(C1-C6)alkyl-; (C1-C6)acyloxy(C1-C6)alkyl-; nitro; cyano(C1-C6)alkyl-; halo(C1-C6)alkyl-; nitro(C1-C6)alkyl-; trifluoromethyl; trifluoromethyl(C1-C6)alkyl-; (C1-C6)acylamino-; (C1-C6)acylamino(C1-C6)alkyl-; (C1-C6)alkoxy(C1-C6)acylamino-; amino(C1-C6)acyl-; amino(C1-C6)acyl(C1-C6)alkyl-; (C1-C6)alkylamino(C1-C6)acyl-; ((C1-C6) alkyl)2amino(C1-C6)acyl-; xe2x80x94CO2R2; xe2x80x94(C1-C6)alkyl-CO2R2; xe2x80x94C(O)N(R2)2; xe2x80x94(C1-C6)alkyl-C(O)N(R2)2; R2ONxe2x95x90; R2ONxe2x95x90(C1-C6)alkyl-; R2ONxe2x95x90CR2(C1-C6)alkyl-; xe2x80x94NR2(OR2); xe2x80x94(C1-C6)alkyl-NR2(OR2); C(O)(NR2OR2); xe2x80x94(C1-C6)alkyl-C(O)(NR2OR2); xe2x80x94S(O)mR2; wherein each R2 is independently selected from hydrogen, (C1-C6)alkyl, aryl, or aryl(C1-C6)alkyl-; R3C(O)Oxe2x80x94, wherein R3 is (C1-C6)alkyl, aryl, or aryl(C1-C6)alkyl-; R3C(O)Oxe2x80x94(C1-C6)alkyl-; R4R5Nxe2x80x94C(O)xe2x80x94Oxe2x80x94; R4R5NS(O)2xe2x80x94; R4R5NS(O)2(C1-C6)alkyl-; R4S(O)2R5Nxe2x80x94; R4S(O)2R5N(C1-C6)alkyl-; wherein m is 0, 1 or 2, and R4 and R5 are each independently selected from hydrogen or (C1-C6)alkyl; xe2x80x94C(xe2x95x90NR6)(N(R4)2); or xe2x80x94(C1-C6)alkyl-C(xe2x95x90NR6)(N(R4)2) wherein R6 represents OR2 or R2 wherein R2 is defined as above;
with the proviso that the cycloalkenyl ring is not aromatic;
with the proviso that R1 must be substituted by at least one of R3C(O)Oxe2x80x94, R3C(O)Oxe2x80x94(C1-C6)alkyl-, R2ONxe2x95x90, R2ONxe2x95x90(C1-C6)alkyl-, R2ONxe2x95x90CR2(C1-C6)alkyl-, xe2x80x94NR2(OR2), R4R5NS(O)2xe2x80x94, R4R5NS(O)2(C1-C6)alkyl-, R4S(O)2R5Nxe2x80x94, or R4S(O)2R5N(C1-C6)alkyl-.
Where R1 is a cyclohexyl or cyclohexenyl ring, the ring is preferably substituted at the 3- or 4-position, and more preferably at the 4-position.
Where R1 is a cyclopentyl or cyclopentenyl ring, the ring is preferably substituted at the 3-position.
In a preferred embodiment, R1 is monosubstituted.
In a further preferred embodiment, R1 is disubstituted.
In a preferred embodiment, R1 is substituted by at least one of R3C(O)Oxe2x80x94 or R3C(O)Oxe2x80x94(C1-C6)alkyl-.
In a further preferred embodiment, R1 is substituted by at least one of R3C(O)Oxe2x80x94.
In a further preferred embodiment, R1 is substituted by at least one of R3C(O)Oxe2x80x94(C1-C6)alkyl-.
In a further preferred embodiment, R1 is substituted by at least one of R2ONxe2x95x90, R2ONxe2x95x90(C1-C6)alkyl-, or R2ONxe2x95x90CR2(C1-C6)alkyl-.
In a further preferred embodiment, R1 is substituted by at least one of R2ONxe2x95x90.
In a further preferred embodiment, R1 is substituted by at least one of xe2x80x94NR2(OR2).
In a further preferred embodiment, R1 is substituted by at least one of R4R5NS(O)2xe2x80x94, R4R5NS(O)2(C1-C6)alkyl-, R4S(O)2R5Nxe2x80x94, or R4S(O)2R5N(C1-C6)alkyl-.
In a further preferred embodiment, R1 is substituted by at least one of R4S(O)2R5Nxe2x80x94.
In a further preferred embodiment, R1 is substituted by at least one of R4S(O)2R5N(C1-C6)alkyl-.
In a further preferred embodiment, R1 is a (C3-C8)cycloalkyl ring or (C5-C8)cycloalkenyl ring, wherein either the cycloalkyl ring or cycloalkenyl ring is substituted by R3C(O)Oxe2x80x94, R3C(O)Oxe2x80x94(C1-C6)alkyl-, R2ONxe2x95x90, R2ONxe2x95x90(C1-C6)alkyl-, R2ONxe2x95x90CR2(C1-C6)alkyl-, xe2x80x94NR2(OR2), R4R5NS(O)2xe2x80x94, R4R5NS(O)2(C1-C6)alkyl-, R4S(O)2R5Nxe2x80x94, or R4S(O)2R5N(C1-C6)alkyl-; wherein R2, R3, R4 and R5 are as defined above;
with the proviso that the cycloalkenyl ring is not aromatic.
In a further preferred embodiment, R1 is a (C3-C8)cycloalkyl ring or (C5-C8)cycloalkenyl ring, wherein either the cycloalkyl ring or cycloalkenyl ring is substituted by one of R3C(O)Oxe2x80x94, R3C(O)Oxe2x80x94(C1-C6)alkyl-, R2ONxe2x95x90, or R4S(O)2R5Nxe2x80x94; wherein R2, R3, R4 and R5 are as defined above;
with the proviso that the cycloalkenyl ring is not aromatic.
In a preferred embodiment, R1 is substituted by R3C(O)Oxe2x80x94 or R3C(O)Oxe2x80x94(C1-C6)alkyl-.
In a further preferred embodiment, R1 is substituted by R3C(O)Oxe2x80x94.
In a further preferred embodiment, R1 is substituted by R3C(O)Oxe2x80x94(C1-C6)alkyl-.
In a further preferred embodiment, R1 is substituted by R2ONxe2x95x90, R2ONxe2x95x90(C1-C6)alkyl-, or R2ONxe2x95x90CR2(C1-C6)alkyl-.
In a further preferred embodiment, R1 is substituted by R2ONxe2x95x90.
In a further preferred embodiment, R1 is substituted by xe2x80x94NR2(OR2).
In a further preferred embodiment, R1 is substituted by R4R5NS(O)2xe2x80x94, R4R5NS(O)2(C1-C6)alkyl-, R4S(O)2R5Nxe2x80x94, or R4S(O)2R5N(C1-C6)alkyl-.
In a further preferred embodiment, R1 is substituted by R4S(O)2R5Nxe2x80x94.
In a further preferred embodiment, R1 is substituted by R4S(O)2R5N(C1-C6)alkyl-.
The (C2-C9)heterocycloalkyl substituent, when present on R1 of the compound of formula I, is preferably a group of the formula: 
wherein m is as defined above, and
Z is CH2, NR2, O, S, SO, or SO2. 
For any of the aforementioned compositions of the present invention, R1 of the compound of formula I is preferably a group of the formula: 
which is substituted as described above for R1;
wherein n is 0, 1, or 2;
wherein the dashed line indicates an optional double bond at that position.
In a further preferred embodiment, n is 0 or 1.
In a further preferred embodiment, n is 0; and the dashed line represents a double bond at that position.
In a further preferred embodiment, n is 1.
In a further preferred embodiment, R1 is substituted by xe2x95x90O, xe2x95x90NOH, CH2OH or 
or a combination thereof.
In a further preferred embodiment, n is 0; R1 is substituted by xe2x95x90NOH; and the dashed line represents a double bond at that position.
In further preferred embodiment, n is 1; and R1 is substituted by xe2x95x90O, xe2x95x90NOH, CH2OH, or 
or a combination thereof.
The present invention further provides a topical pharmaceutical composition for lightening skin or reducing the pigmentation of skin in a human, comprising a pharmaceutically acceptable carrier, and a skin-lightening or pigmentation-reducing effective amount of a compound selected from the group consisting of:
4-(2,4-Dihydroxyphenyl)cyclohexanone oxime;
O-Methyl-4-(2,4-dihydroxyphenyl)cyclohexanone oxime;
O-Benzyl-4-(2,4-dihydroxyphenyl)cyclohexanone oxime;
3-(2,4-Dihydroxyphenyl)-2-cyclohexen-1-one oxime;
(xc2x1)-3-(2,4-Dihydroxyphenyl)cyclohexanone oxime;
(xc2x1)-N-[3-(2,4-Dihydroxyphenyl)cyclohexyl]methanesulfonamide;
(xc2x1)-4-[3-(Hydroxyamino)cyclohexyl]-1,3-benzenediol;
(xc2x1)-O-Methyl-3-(2,4-dihydroxyphenyl)cyclohexanone oxime;
(xc2x1)-O-Benzyl-3-(2,4-dihydroxyphenyl)cyclohexanone oxime;
3-(2,4-Dihydroxyphenyl)-2-cyclopentenone oxime;
(xc2x1)-3-(2,4-Dihydroxyphenyl)cyclopentanone oxime;
and a pharmaceutically acceptable salt thereof.
The present invention further provides a topical pharmaceutical composition for lightening skin or reducing the pigmentation of skin in a human, comprising a pharmaceutically acceptable carrier, and a skin-lightening or pigmentation-reducing effective amount of a compound selected from the group consisting of:
cis-N-[4-(2,4-Dihydroxyphenyl)cyclohexyl]-1-butanesulfonamide;
trans-N-[4-(2,4-Dihydroxyphenyl)cyclohexyl]methanesulfonamide;
cis-N-[4-(2,4-Dihydroxyphenyl)cyclohexyl]methanesulfonamide;
trans-4-(2,4-Dihydroxyphenyl)cyclohexyl) 4-(dimethylamino)benzoate;
trans-4-(2,4-Dihydroxyphenyl)cyclohexyl 4-tert-butylbenzoate;
trans-4-(2,4-Dihydroxyphenyl)cyclohexyl 4-fluorobenzoate;
trans-4-(2,4-Dihydroxyphenyl)cyclohexyl 4-trifluoromethylbenzoate;
trans-4-(2,4-Dihydroxyphenyl)cyclohexyl 4-methoxybenzoate;
trans-4-(2,4-Dihydroxyphenyl)cyclohexyl 4-methylbenzoate;
trans-4-(2,4-Dihydroxyphenyl)cyclohexyl 4-chlorobenzoate;
trans-4-(2,4-Dihydroxyphenyl)cyclohexyl 3,4-dimethylbenzoate;
trans-4-(2,4-Dihydroxyphenyl)cyclohexyl 3,4-dichlorobenzoate;
[4-(2,4-Dihydroxyphenyl)cyclohexyl]methyl propionate;
cis/trans-4-[4-(hydroxyamino)cyclohexyl]-1,3-benzenediol;
trans-4-[4-(methoxyamino)cyclohexyl]-1,3-benzenediol;
and a pharmaceutically acceptable salt thereof.
In a further preferred embodiment, the skin-lightening or pigmentation-reducing effective amount of a compound of formula I of the pharmaceutical composition of the present invention is a tyrosinase-inhibiting effective amount of the compound.
The present invention further provides a topical pharmaceutical composition for inhibiting tyrosinase in a human, comprising a pharmaceutically acceptable carrier, and a tyrosinase-inhibiting effective amount of a compound selected from among the compounds of any of the aforementioned pharmaceutical compositions of the present invention.
The present invention further provides a method of lightening skin or reducing the pigmentation of skin in a human, comprising administering to said human a skin-lightening or skin pigmentation-reducing effective amount of a compound of formula l: 
or a pharmaceutically acceptable salt thereof, wherein:
R1 is a (C3-C8)cycloalkyl ring or (C5-C8)cycloalkenyl ring, wherein either the cycloalkyl ring or cycloalkenyl ring is substituted by one to three substituents independently selected from the group consisting of cyano; halo; (C1-C6)alkyl; aryl; (C2-C9)heterocycloalkyl; (C2-C9)heteroaryl; aryl(C1-C6)alkyl-; xe2x95x90O; xe2x95x90CHO(C1-C6)alkyl; amino; hydroxy; (C1-C6)alkoxy; aryl(C1-C6)alkoxy-; (C1-C6)acyl; (C1-C6)alkylamino-; aryl(C1-C6)alkylamino-; amino(C1-C6)alkyl-; (C1-C6)alkoxy-COxe2x80x94NHxe2x80x94; (C1-C6)alkylamino-COxe2x80x94; (C2-C6)alkenyl; (C2-C6)alkynyl; hydroxy(C1-C6)alkyl-; (C1-C6)alkoxy(C1-C6)alkyl-; (C1-C6)acyloxy(C1-C6)alkyl-; nitro; cyano(C1-C6)alkyl-; halo(C1-C6)alkyl-; nitro(C1-C6)alkyl-; trifluoromethyl; trifluoromethyl(C1-C6)alkyl-; (C1-C6)acylamino-; (C1-C6)acylamino(C1-C6)alkyl-; (C1-C6)alkoxy(C1-C6)acylamino-; amino(C1-C6)acyl-; amino(C1-C6)acyl(C1-C6)alkyl-; (C1-C6)alkylamino(C1-C6)acyl-; ((C1-C6) alkyl)2amino(C1-C6)acyl-; xe2x80x94CO2R2; xe2x80x94(C1-C6)alkyl-CO2R2; xe2x80x94C(O)N(R2)2; xe2x80x94(C1-C6)alkyl-C(O)N(R2)2; R2ONxe2x95x90; R2ONxe2x95x90(C1-C6)alkyl-; R2ONxe2x95x90CR2(C1-C6)alkyl-; xe2x80x94NR2(OR2); xe2x80x94(C1-C6)alkyl-NR2(OR2); xe2x80x94C(O)(NR2OR2); xe2x80x94(C1-C6)alkyl-C(O)(NR2OR2); xe2x80x94S(O)mR2; wherein each R2 is independently selected from hydrogen, (C1-C6)alkyl, aryl, or aryl(C1-C6)alkyl-; R3C(O)Oxe2x80x94, wherein R3 is (C1-C6)alkyl, aryl, or aryl(C1-C6)alkyl-; R3C(O)Oxe2x80x94(C1-C6)alkyl-; R4R5Nxe2x80x94C(O)xe2x80x94Oxe2x80x94; R4R5NS(O)2xe2x80x94; R4R5NS(O)2(C1-C6)alkyl-; R4S(O)2R5Nxe2x80x94; R4S(O)2R5N(C1-C6)alkyl-; wherein m is 0, 1 or 2, and R4 and R5 are each independently selected from hydrogen or (C1-C6)alkyl; xe2x80x94C(xe2x95x90NR6)(N(R4)2); or xe2x80x94(C1-C6)alkyl-C(xe2x95x90NR6)(N(R4)2) wherein R6 represents OR2 or R2 wherein R2 is defined as above;
with the proviso that the cycloalkenyl ring is not aromatic;
with the proviso that when R1 is a (C5-C8)cycloalkyl ring, or when R1 is a (C5-C8)cycloalkenyl ring having the following structure: 
wherein n is 0, 1, 2 or 3, where such (C5-C8)cycloalkyl ring or (C5-C8)cycloalkenyl ring is substituted by hydroxy, (C1-C6)alkoxy-, aryl(C1-C6)alkoxy-, xe2x80x94OC(O)(C1-C6)alkyl, xe2x80x94OC(O)aryl(C1-C6)alkyl, xe2x80x94OC(O)phenyl, halo, (C1-C6)alkyl-, aryl(C1-C6)alkyl-, xe2x80x94SH, xe2x80x94S(C1-C6)alkyl, aryl(C1-C6)alkyl-Sxe2x80x94, xe2x80x94NH2, xe2x80x94NH(C1-C6)alkyl, or aryl(C1-C6)alkyl-HNxe2x80x94; then the (C5-C8)cycloalkyl ring or the (C5-C8)cycloalkenyl ring must be di- or tri-substituted.
Where R1 is a cyclohexyl or cyclohexenyl ring, the ring is preferably substituted at the 3- or 4-position, and more preferably at the 4-position.
Where R1 is a cyclopentyl or cyclopentenyl ring, the ring is preferably substituted at the 3-position.
In a preferred embodiment, R1 is monosubstituted.
In a further preferred embodiment, R1 is disubstituted.
In a preferred embodiment, R1 of the compound of the method is substituted by at least one of R3C(O)Oxe2x80x94, R3C(O)Oxe2x80x94(C1-C6)alkyl-, R2ONxe2x95x90, R2ONxe2x95x90(C1-C6)alkyl-, R2ONxe2x95x90CR2(C1-C6)alkyl-, xe2x80x94NR2(OR2), R4R5NS(O)2xe2x80x94, R4R5NS(O)2(C1-C6)alkyl-, R4S(O)2R5Nxe2x80x94, or R4S(O)2R5N(C1-C6)alkyl-.
In a further preferred embodiment, R1 of the compound of the method is substituted by at least one of R3C(O)Oxe2x80x94 or R3C(O)Oxe2x80x94(C1-C6)alkyl-.
In a further preferred embodiment, R1 is substituted by at least one of R3C(O)Oxe2x80x94.
In a further preferred embodiment, R1 is substituted by at least one of R3C(O)Oxe2x80x94(C1-C6)alkyl-.
In a further preferred embodiment, R1 of the compound of the method is substituted by at least one of R2ONxe2x95x90, R2ONxe2x95x90(C1-C6)alkyl-, or R2ONxe2x95x90CR2(Cxe2x80x94C6)alkyl-.
In a further preferred embodiment, R1 of the compound of the method is substituted by at least one of R2ONxe2x95x90.
In a further preferred embodiment, R1 of the compound of the method is substituted by at least one of xe2x80x94NR2(OR2).
In a further preferred embodiment, R1 of the compound of the method is substituted by at least one of R4R5NS(O)2xe2x80x94, R4R5NS(O)2(C1-C6)alkyl-, R4S(O)2R5Nxe2x80x94, or R4S(O)2R5N(C1-C6)alkyl-.
In a further preferred embodiment, R1 of the compound of the method is substituted by at least one of R4S(O)2R5Nxe2x80x94.
In a further preferred embodiment, R1 of the compound of the method is substituted by at least one of R4S(O)2R5N(C1-C6)alkyl-.
In a further preferred embodiment, R1 of the compound of the method is substituted by at least one of hydroxy(C1-C6)alkyl-.
In a further preferred embodiment, R1 is a (C3-C8)cycloalkyl ring or (C5-C8)cycloalkenyl ring, wherein either the cycloalkyl ring or cycloalkenyl ring is substituted by one of R3C(O)Oxe2x80x94, R3C(O)Oxe2x80x94(C1-C6)alkyl-, R2ONxe2x95x90, R2ONxe2x95x90(C1-C6)alkyl-, R2ONxe2x95x90CR2(C1-C6)alkyl-, xe2x80x94NR2(OR2), R4R5NS(O)2xe2x80x94, R4R5NS(O)2(C1-C6)alkyl-, R4S(O)2R5Nxe2x80x94, or R4S(O)2R5N(C1-C6)alkyl-; wherein R2, R3, R4 and R5 are as defined above.
In a further preferred embodiment, R1 is a (C3-C8)cycloalkyl ring or (C5-C8)cycloalkenyl ring, wherein either the cycloalkyl ring or cycloalkenyl ring is substituted by one of R3C(O)Oxe2x80x94, R3C(O)Oxe2x80x94(C1-C6)alkyl-, R2ONxe2x95x90, or R4S(O)2R5Nxe2x80x94; wherein R2, R3, R4 and R5 are as defined above.
In a preferred embodiment, R1 is substituted by one of R3C(O)Oxe2x80x94 or R3C(O)Oxe2x80x94(C1-C6)alkyl-.
In a further preferred embodiment, R1 is substituted by one of R3C(O)Oxe2x80x94.
In a further preferred embodiment, R1 is substituted by one of R3C(O)Oxe2x80x94(C1-C6)alkyl-.
In a further preferred embodiment, R1 is substituted by one of R2ONxe2x95x90, R2ONxe2x95x90(C1-C6)alkyl-, or R2ONxe2x95x90CR2(C1-C6)alkyl-.
In a further preferred embodiment, R1 is substituted by one of R2ONxe2x95x90.
In a further preferred embodiment, R1 is substituted by one of xe2x80x94NR2(OR2).
In a further preferred embodiment, R1 is substituted by one of R4R5NS(O)2xe2x80x94, R4R5NS(O)2(C1-C6)alkyl-, R4S(O)2R5Nxe2x80x94, or R4S(O)2R5N(C1-C6)alkyl-.
In a further preferred embodiment, R1 is substituted by one of R4S(O)2R5Nxe2x80x94.
In a further preferred embodiment, R1 is substituted by one of R4S(O)2R5N(C1-C6)alkyl-.
In a further preferred embodiment, R1 of the compound of the method is substituted by one of hydroxy(C1-C6)alkyl-.
The (C2-C9)heterocycloalkyl substituent, when present on R1 of the compound of formula 1, is preferably a group of the formula: 
wherein m is as defined above, and
Z is CH2, NR2, O, S, SO, or SO2.
For any of the aforementioned methods of the present invention, R1 of the compound of formula I is preferably a group of the formula: 
which is substituted as described above for R1;
wherein n is 0, 1, or 2;
wherein the dashed line indicates an optional double bond at that position.
In a further preferred embodiment, n is 0 or 1.
In a further preferred embodiment, n is 0; and the dashed line represents a double bond at that position.
In a further preferred embodiment, n is 1.
In a further preferred embodiment, R1 is substituted by xe2x95x90O, xe2x95x90NOH, CH2OH or 
or a combination thereof.
In a further preferred embodiment, n is 0; R1 is substituted by xe2x95x90NOH; and the dashed line represents a double bond at that position.
In further preferred embodiment, n is 1; and R1 is substituted by xe2x95x90O, xe2x95x90NOH, CH2OH, or 
or a combination thereof.
In a preferred embodiment, the method of the present invention comprises administering to a human a skin-lightening or pigmentation-reducing effective amount of a compound selected from the group consisting of:
4-(2,4-Dihydroxyphenyl)cyclohexanone;
4-(2,4-Dihydroxyphenyl)cyclohexanone oxime;
O-Methyl-4-(2,4-dihydroxyphenyl)cyclohexanone oxime;
O-Benzyl-4-(2,4-dihydroxyphenyl)cyclohexanone oxime;
3-(2,4-dihydroxyphenyl)-2-cyclohexen-1-one;
(xc2x1)-3-(2,4-Dihydroxyphenyl)cyclohexanone;
3-(2,4-Dihydroxyphenyl)-2-cyclohexen-1-one oxime;
(xc2x1)-3-(2,4-Dihydroxyphenyl)cyclohexanone oxime;
(xc2x1)-4-[3-(1-Piperazinyl)cyclohexyl]-1,3-benzenediol;
(xc2x1)-N-[3-(2,4-Dihydroxyphenyl)cyclohexyl]methanesulfonamide;
(xc2x1)-4-[3-(Hydroxymethyl)cyclohexyl]-1,3-benzenediol;
(xc2x1)-4-[3-(Hydroxyamino)cyclohexyl]-1,3-benzenediol;
cis/trans-4-[4-(Hydroxymethyl)cyclohexyl]-1,3-benzenediol;
cis/trans-4-(4-Hydroxy-4-methylcyclohexyl)-1,3-benzenediol;
(xc2x1)-O-Methyl-3-(2,4-dihydroxyphenyl)cyclohexanone oxime;
(xc2x1)-3-(2,4-Dihydroxyphenyl)-1-methylcyclohexanol;
(xc2x1)-O-Benzyl-3-(2,4-dihydroxyphenyl)cyclohexanone oxime;
3-(2,4-Dihydroxyphenyl)-2-cyclopentenone oxime;
(xc2x1)-3-(2,4-Dihydroxyphenyl)cyclopentanone;
(xc2x1)-3-(2,4-Dihydroxyphenyl)cyclopentanone oxime;
and a pharmaceutically acceptable salt thereof.
In a further preferred embodiment, the method of the present invention comprises administering to a human a skin-lightening or pigmentation-reducing effective amount of a compound selected from the group consisting of:
4-(2,4-Dihydroxyphenyl)-3-cyclohexen-1-one;
cis/trans-N-[4-(2,4-Dihydroxyphenyl)cyclohexyl]acetamide;
cis-N-[4-(2,4-Dihydroxyphenyl)cyclohexyl]-1-butanesulfonamide;
trans-N-[4-(2,4-Dihydroxyphenyl)cyclohexyl]methanesulfonamide;
cis-N-[4-(2,4-Dihydroxyphenyl)cyclohexyl]methanesulfonamide;
4-[4-(4-Hydroxyphenyl)cyclohexyl]-1,3-benzenediol;
cis/trans-Methyl [4-(2,4-dihydroxyphenyl)cyclohexyl]acetate;
trans-Methyl [4-(2,4-dihydroxyphenyl)cyclohexyl]acetate;
cis-Methyl [4-(2,4-dihydroxyphenyl)cyclohexyl]acetate;
trans-[4-(2,4-Dihydroxyphenyl)cyclohexyl]acetic acid;
cis-[4-(2,4-Dihydroxyphenyl)cyclohexyl]acetic acid;
cis/trans-[4-(2,4-Dihydroxyphenyl)cyclohexyl]acetic acid;
cis/trans-[4-(2,4-Dihydroxyphenyl)cyclohexyl]acetonitrile;
cis/trans-4-[4-(2-Aminoethyl)cyclohexyl]-1,3-benzenediol;
(xc2x1)-4-(3,3-Difluorocyclohexyl)-1,3-benzenediol;
(xc2x1)-3-(2,4-Dihydroxyphenyl)cyclohexanecarboxamide;
(xc2x1)-3-(2,4-Dihydroxyphenyl)-N-hydroxycyclohexanecarboxamide;
(xc2x1)-3-(2,4-Dihydroxyphenyl)-N-ethylcyclohexanecarboxamide;
(xc2x1)-4-[3-Hydroxy-3-(hydroxymethyl)cyclohexyl]-1,3-benzenediol;
(xc2x1)-N-[3-(2,4-dihydroxyphenyl)cyclohexyl]acetamide;
trans-4-(2,4-Dihydroxyphenyl)cyclohexyl) 4-(dimethylamino)benzoate;
cis/trans-4-(2,4-Dihydroxyphenyl)cyclohexanecarboxylic acid;
trans-4-(2,4-Dihydroxyphenyl)cyclohexyl ethylcarbamate;
trans-4-(2,4-Dihydroxyphenyl)cyclohexyl cyclohexylcarbamate;
trans-4-(2,4-Dihydroxyphenyl)cyclohexyl 4-tert-butylbenzoate;
trans-4-(2,4-Dihydroxyphenyl)cyclohexyl 4-fluorobenzoate;
trans-4-(2,4-Dihydroxyphenyl)cyclohexyl 4-trifluoromethylbenzoate;
trans-4-(2,4-Dihydroxyphenyl)cyclohexyl 4-methoxybenzoate;
trans-4-(2,4-Dihydroxyphenyl)cyclohexyl 4-methylbenzoate;
trans-4-(2,4-Dihydroxyphenyl)cyclohexyl 4-chlorobenzoate;
trans-4-(2,4-Dihydroxyphenyl)cyclohexyl 3,4-dimethylbenzoate;
trans-4-(2,4-Dihydroxyphenyl)cyclohexyl 3,4-dichlorobenzoate;
trans-4-[4-(Phenylsulfanyl)cyclohexyl]-1,3-benzenediol;
trans-4-[4-(Phenylsulfonyl)cyclohexyl]-1,3-benzenediol;
[4-(2,4-Dihydroxyphenyl)cyclohexyl]methyl propionate;
ethyl 4-(2,4-dihydroxyphenyl)-1-hydroxycyclohexane carboxylate;
cis/trans-4-[4-(hydroxyamino)cyclohexyl]-1,3-benzenediol;
trans-4-[4-(methoxyamino)cyclohexyl]-1,3-benzenediol;
and a pharmaceutically acceptable salt thereof.
In a preferred embodiment, the method is carried out by administering a skin-lightening or pigmentation-reducing effective amount of a compound of the present invention to a human in need of said treatment.
In another preferred embodiment, the skin-lightening or pigmentation-reducing effective amount of a compound of the method of the present invention is a tyrosinase-inhibiting effective amount of the compound.
The present invention further provides a method of inhibiting tyrosinase in a human, comprising administering to said human a tyrosinase-inhibiting effective amount of a compound selected from among the compounds used in any of the aforementioned methods of the present invention. In a preferred embodiment, the method is carried out by administering a tyrosinase-inhibiting effective amount of a compound of the present invention to a human in need of said treatment.
The present invention further provides a topical or transdermal pharmaceutical composition for the treatment of an inflammatory disorder such as psoriasis, dermatitis or acne, or for the treatment of dandruff, in a human, comprising a pharmaceutically acceptable carrier, and an amount of a compound of formula I, or a pharmaceutically acceptable salt thereof, used in any of the aforementioned pharmaceutical compositions of the present invention, which amount is effective in treating such disorder or condition.
The present invention further provides a method of treating inflammatory disorders, such as psoriasis, dermatitis or acne, or a method of treating dandruff, in a human, comprising administering to said human an amount of a compound of formula I or a pharmaceutically acceptable salt thereof, used in any of the aforementioned methods of the present invention, which amount is effective in treating such disorder or condition.
The present invention further provides a use of any of the compounds used in any of the aforementioned methods of the present invention, or any of the compounds used in any of the aforementioned pharmaceutical compositions of the present invention, to prepare a medicament useful in lightening skin or reducing pigmentation of skin in a human.
The term xe2x80x9calkylxe2x80x9d, as used herein, unless otherwise indicated, includes saturated monovalent hydrocarbon radicals having straight, branched or cyclic moieties or combinations thereof. Any substituents or functional groups on the alkyl group, as indicated herein, can be substituted anywhere on the alkyl group.
The term xe2x80x9carylxe2x80x9d, as used herein, refers to phenyl or naphthyl optionally substituted with one or more substituents, preferably from zero to two substituents, independently selected from halogen, OH, (C1-C6)alkyl, (C1-C6) alkoxy, amino, (C1-C6)alkylamino, di-((C1-C6)alkyl))amino, nitro, cyano and trifluoromethyl. Any substituents or functional groups on the aryl group, as indicated herein, can be substituted anywhere on the aryl group.
The term xe2x80x9cone or more substituentsxe2x80x9d, as used herein, refers to a number of substituents that equals from one to the maximum number of substituents possible based on the number of available bonding sites.
The xe2x80x9chaloxe2x80x9d, as used herein, refers to halogen and, unless otherwise indicated, includes chloro, fluoro, bromo and iodo.
The term xe2x80x9cacylxe2x80x9d, as used herein, unless otherwise indicated, includes a radical of the general formula RCO wherein R is alkyl, alkoxy, aryl, arylalkyl, or arylalkyloxy and the terms xe2x80x9calkylxe2x80x9d or xe2x80x9carylxe2x80x9d are as defined above.
The term xe2x80x9cacyloxyxe2x80x9d, as used herein, includes O-acyl groups wherein xe2x80x9cacylxe2x80x9d is as defined above.
(C2-C9)Heterocycloalkyl, when used herein, refers to pyrrolidinyl, tetrahydrofuranyl, dihydrofuranyl, tetrahydropyranyl, pyranyl, thiopyranyl, aziridinyl, oxiranyl, methylenedioxyl, chromenyl, isoxazolidinyl, 1,3-oxazolidin-3-yl, isothiazolidinyl, 1,3-thiazolidin-3-yl, 1,2-pyrazolidin-2-yl, 1,3-pyrazolidin-1-yl, piperidinyl, thiomorpholinyl, 1,2-tetrahydrothiazin-2-yl, 1,3-tetrahydrothiazin-3-yl, tetrahydrothiadiazinyl, morpholinyl, 1,2-tetrahydrodiazin-2-yl, 1,3-tetrahydrodiazin-1-yl, tetrahydroazepinyl, piperazinyl, chromanyl, etc. One of ordinary skill in the art will understand that the connection of said (C2-C9)heterocycloalkyl ring can be through a carbon atom or through a nitrogen heteroatom where possible.
(C2-C9)Heteroaryl, when used herein, refers to furyl, thienyl, thiazolyl, pyrazolyl, isothiazolyl, oxazolyl, isoxazolyl, pyrrolyl, triazolyl, tetrazolyl, imidazolyl, 1,3,5-oxadiazolyl, 1,2,4-oxadiazolyl, 1,2,3-oxadiazolyl, 1,3,5-thiadiazolyl, 1,2,3-thiadiazolyl, 1,2,4-thiadiazolyl, pyridyl, pyrimidyl, pyrazinyl, pyridazinyl, 1,2,4-triazinyl, 1,2,3-triazinyl, 1,3,5-triazinyl, pyrazolo[3,4-b]pyridinyl, cinnolinyl, pteridinyl, purinyl, 6,7-dihydro-5H-[1]pyridinyl, benzo[b]thiophenyl, 5, 6, 7, 8-tetrahydro-quinolin-3-yl, benzoxazolyl, benzothiazolyl, benzisothiazolyl, benzisoxazolyl, benzimidazolyl, thianaphthenyl, isothianaphthenyl, benzofuranyl, isobenzofuranyl, isoindolyl, indolyl, indolizinyl, indazolyl, isoquinolyl, quinolyl, phthalazinyl, quinoxalinyl, quinazolinyl, benzoxazinyl, etc. One of ordinary skill in the art will understand that the connection of said (C2-C9)heterocycloalkyl rings can be through a carbon atom or through a nitrogen heteroatom where possible.
Compounds of formula I may contain chiral centers and therefore may exist in different enantiomeric and diastereomeric forms. This invention relates to all optical isomers, stereoisomers and tautomers of the compounds of formula I, and mixtures thereof, and to all pharmaceutical compositions and methods of treatment defined above that contain or employ them, respectively.
Formula I, as defined above, also includes compounds identical to those depicted but for the fact that one or more hydrogen, carbon or other atoms are replaced by isotopes thereof. Such compounds may be useful as research and diagnostic tools in metabolism pharmacokinetic studies and in binding assays.
The present invention also relates to the pharmaceutically acceptable acid addition and base salts of any of the aforementioned compounds of formula I. The acids which are used to prepare the pharmaceutically acceptable acid addition salts of the aforementioned base compounds of this invention are those which form non-toxic acid addition salts, i.e., salts containing pharmacologically acceptable anions, such as the hydrochloride, hydrobromide, hydroiodide, nitrate, sulfate, bisulfate, phosphate, acid phosphate, acetate, lactate, citrate, acid citrate, tartrate, bitartrate, succinate, maleate, fumarate, gluconate, saccharate, benzoate, methanesulfonate, ethanesulfonate, benzenesulfonate, p-toluenesulfonate and pamoate (i.e., 1,1-methylene-bis-(2-hydroxy-3-naphthoate)) salts.
As used herein, a xe2x80x9cskin-lightening or pigmentation reducing amount of a compound of formula Ixe2x80x9d, and the like, means an amount or concentration of the compound capable of detectably lightening skin or reducing pigmentation in a human, as determined by any standard assay. The active compound is typically administered in a pharmaceutical composition and for a standard course of treatment that produces the desired result of skin depigmentation.
As used herein, a xe2x80x9ctyrosinase-inhibiting effective amount of a compound of formula Ixe2x80x9d, and the like, means an amount or concentration of the compound capable of detectably inhibiting tyrosinase activity in a human, as determined by any standard assay, such as those described below.
As used herein, an xe2x80x9camount of a compound of formula I capable of treating an inflammatory disorder such as psoriasis, dermatitis or acne, or treating dandruffxe2x80x9d, and the like, means an amount or concentration of the compound capable of detectably ameliorating, reducing, eliminating, slowing, or preventing the progression of, any symptom or condition associated with or caused by such disorder or condition, in a human, as determined by any standard assay.
The compounds of formula I may be prepared as described in the following reaction schemes and discussion. Unless otherwise indicated, n, m, R2, R3, R4, R5, Z, and structural formula I in the reaction schemes and discussion that follow are as defined above. 
Y, YI, YII shown in the schemes above each independently represents any of the various substituents on R1 as defined above, or hydrogen as appropriate.
Reaction Schemes 1 through 12 illustrate various methods of synthesizing compounds of formula I. PG refers to a protecting group.
Referring to Scheme 1, compounds of formula (2) can be formed by protecting commercially available 4-bromoresorcinol (1). A suitable protecting group such as methoxymethyl (MOM) can be introduced by conventional methods that are well known to those skilled in the art. For example, alkylation of 4-bromoresorcinol can occur with two equivalents of methoxymethyl chloride in the presence of diisopropylamine in a halogenated solvent at about 0xc2x0 C. to room temperature.
Compounds of general formula (3) can be obtained using conventional methods. For example, the reaction of compounds of formula (2) with n-butyllithium in the presence of N,N,Nxe2x80x2,Nxe2x80x2-tetramethylethylenediamine in a suitable solvent such as tetrahydrofuran, followed by quenching with triisopropyl borate and hydrolysing with aqueous acid, can yield compounds of formula (3).
Compounds of general formula (5) can be obtained using conventional methods. For example, the treatment of compounds of formula (4) with triphenylphosphine and bromine in a chlorinated solvent will yield compounds of formula (5). Compound (4) where n=1 is commercially available (Aldrich, Milwaukee, Wis., USA).
Compounds of formula (6) can be obtained by reacting compounds of formula (3) with compounds of formula (5) under Suzuki coupling conditions. For example, the Suzuki reaction can be carried out using palladium tetrakis (triphenylphosphine)palladium (five mole percent), sodium carbonate (two equivalents) and heating in a suitable solvent system (e.g., dimethoxyethane/water) at about 80xc2x0 C. Conversion of compounds of formula (6) to compounds of formula (8) can occur under standard reducing conditions, such as, e.g., hydrogen gas and a metal catalyst such as rhodium on alumina, at about room temperature and atmospheric pressure. Deprotection of compounds of formula (6) or (8) under suitable conditions, e.g., where the protecting group is MOM, heating at 50xc2x0 C. in methanol with acidic Dowex, gives compounds of formula I where R1 is substituted with xe2x95x90O (7), (9). Compounds of formula (7) or (9) can be further derivatised under standard conditions to yield resorcinols of formula I where R1 is substituted with xe2x95x90NOR 2. For example, heating compounds of formula (7) in a suitable solvent (e.g., ethanol) at about 80xc2x0 C. with the required hydroxylamine hydrochloride salt and triethylamine yields the analogues of formula I. Compounds of formula I where R1 is substituted with NHOR2 can be prepared from compounds of formula I where R1 is substituted with xe2x95x90NOR2 by a reduction under standard reaction conditions, e.g., sodium cyanoborohydride in acetic acid at or about room temperature.
Compounds of formula (8) can be further derivatised under standard conditions to yield resorcinols of formula I where R1 is disubstituted with fluoro. For example, treating compounds of formula (8) with diethylaminosulfur trifluoride in a suitable solvent, e.g. dimethoxyethane, after suitable deprotection, would give analogues of formula I.
Referring to Scheme 2, compounds of the general formula (10) are well known and can be obtained using conventional methods (see, e.g., Crombie et al., 1982, J. Chem. Soc. Perkin Trans. I, 1485). Compounds of formula (11) can be obtained from the reaction of compounds of formula (2) with n-butyllithium in the presence of N,N,Nxe2x80x2,Nxe2x80x2-tetramethylethylenediamine in an ethereal solvent, followed by the addition of a compound of formula (10). Dehydration of compounds of formula (11) under standard conditions, e.g., heating compounds of formula (11) at about 110xc2x0 C. in a Dean-Stark apparatus in the presence of camphor sulfonic acid in a suitable solvent (e.g., toluene), yields compounds of formula (12). Hydrogenation under standard conditions, e.g., using hydrogen gas and palladium on charcoal in ethanol, yields compounds of the general formula (13). Deprotection under suitable conditions yields resorcinols of formula I where R1 is substituted with xe2x95x90O (14). Compounds of formula (14) can be further derivatised under standard conditions to yield resorcinols of formula I where R1 is substituted with xe2x95x90NOR2. For example, heating compounds of formula (14) in a suitable solvent (e.g., ethanol) at about 80xc2x0 C. with the required hydroxylamine hydrochloride salt and triethylamine yields analogues of formula 1. Further reduction under standard conditions would yield compounds of formula 1, where R1 is substituted with NHOR2. Compounds of formula (14) can also be reprotected with a suitable protecting group such as tert-butyldimethylsilyl under standard reaction conditions to yield compounds of formula (15).
Compounds of formula (15) can be further derivatised using standard reaction conditions. For example, methylenation using an appropriate Wittig will yield compounds of formula (16), e.g., treatment of methyltriphenylphosphonium bromide with potassium t-butoxide in a suitable solvent (e.g., tetrahydrofuran) at a temperature between xe2x88x9278xc2x0 C. and 0xc2x0 C., followed by the addition of a compound of formula (15) will yield compounds of formula (16). Subsequent conversion to compounds of formula (18) under standard conditions, e.g. hydroboration, to give compounds of formula (17), and further oxidation using suitable conditions, such as pyridinium dichromate in dimethylformamide at room temperature, gives compounds of formula (18). Compounds of formula (17) can be treated with an alkyl bromide in a suitable solvent (e.g., acetone) in the presence of potassium carbonate to yield compounds of formula I where R1 is substituted with an ether group after suitable deprotection has taken place, e.g. when the protecting group is tert-butyldimethylsilyl, tetrabutylammonium fluoride in tetrahydrofuran can be used. Alternatively, compounds of formula (17) can also be esterified under standard conditions, e.g. treatment with an acid chloride in the presence of triethylamine in a chlorinated solvent at about room temperature. Compounds of formula (18) can be derivatised to form analogues such as esters and amides under conditions well known to those with skill in the art. For example, conditions to form amides may involve treating compounds of formula (18) with iso-butylchloroformate and triethylamine in a chlorinated solvent at about 0xc2x0 C., followed by the addition of a suitable amine. Deprotection under suitable conditions will yield compounds of formula I where R1 is substituted with an amide. Deprotection of compounds of formula (16), (17) and (18) under standard conditions also provides compounds of formula I where R1 is substituted with methylene, hydroxylmethyl or a carboxylic acid, respectively.
Referring to Scheme 3, compounds of formula (20) can be prepared starting with compound (19), which is commercially available. Conversion to compounds of formula (20) can occur under standard conditions such as, for example, where the protecting group is benzyl, condensation can occur between compound (19) and benzyl alcohol with the removal of water using a Dean-Stark apparatus in conjunction with well known methodology. Condensation of compounds of formula (20) with compounds of formula (10) can occur using standard techniques, for example, treatment of compounds of formula (20) with a base such as lithium diisopropylamide in an ethereal solvent followed by the addition of a compound of formula (10) would give compounds of formula (21). Treatment of compounds of formula (21) with a suitable reagent such as N-bromosuccinimide in a chlorinated solvent at about room temperature can give compounds of formula (22). Compounds of formula (23) can then be generated from compounds of formula (22) under suitable conditions. Such conditions can involve treating compounds of formula (22) with a base such as 1,8-diazobicyclo[5.4.0]undec-7-ene in a suitable solvent such as N,N-dimethylformamide at about 140xc2x0 C. Treatment of compounds of formula (23) to standard hydrogenation conditions, e.g., hydrogen gas and palladium on charcoal in ethanol, yields compounds of the general formula (24) when the protecting group is benzyl. Compounds of formula (14) can then be obtained by treating compounds of formula (24) to acidic conditions.
Conversion of compounds of formula (14) to compounds of formula I may involve the need to use protecting groups that will be obvious to those of skill in the art. Some examples of such compounds of formula I are illustrated in Scheme 3. Conversion of compounds of formula (15) to compounds of formula I may involve the reduction of the ketone moiety under standard conditions, e.g., sodium borohydride in ethanol. Further derivitisation can occur, e.g. using chemistry described elsewhere in this document, to give compounds of formula I where Y1 may be alkyl, acyl or a carbonylamino. In examples where protecting groups have been used, suitable deprotection will be required to yield compounds of formula I.
Alternatively, compounds of formula (15) can be manipulated to give compounds of formula I where R1 is substituted with an amide or sulfonamide. Treatment of compounds of formula (15) with benzylamine under reductive amination conditions, e.g., one equivalent of sodium triacetoxyborohydride in a suitable solvent (dichloroethane) followed by hydrogenolysis under standard conditions, e.g., palladium on charcoal, hydrogen gas, ethanol, provides compounds of formula (25). Synthesis of compounds of formula I can be obtained using conventional methods. For example, compounds of formula (25) can react with sulfonyl chlorides and acid chlorides in a chlorinated solvent in the presence of a base (e.g. triethylamine) at about room temperature. Deprotection using suitable reaction conditions provides compounds of formula I where Y is a sulfonamide or amide group.
Referring to Scheme 4, compounds of formula (26) can be synthesized using standard methods. For example, compounds of formula (6) or (8) can be homologated using a Wittig reaction and further manipulated as described above to yield compounds of formula 1. Compounds of formula (26) or (16) from Scheme 2 can also undergo dihydroxylation under standard conditions, e.g. catalytic osmium tetroxide and N-methyl morpholine in an ethereal solvent, and after suitable deprotection yield compounds of formula I where R1 is substituted with xe2x80x94(OH)(CH2OH).
Referring to Scheme 5, compounds of formula (29) can be obtained by reacting compounds (6) or (8) as described above in Scheme 3. Compounds of formulae (29) and (25) can also be derivatised by treating with an alkylating agent, e.g., an alkyl iodide in a chlorinated solvent in the presence of triethylamine at about room temperature, to give compound (30) prior to sulfonylation or amide bond formation and deprotection, to yield compounds of formula I wherein Y is xe2x80x94N(R5)SO2R4 or equivalent amide where R5 is not hydrogen.
Referring to Scheme 6, compounds of formula (6), (8) or (9), (14) or (15) can be treated with a suitable organometallic reagent, such as a Grignard reagent, in an ethereal solvent at a temperature between xe2x88x9278xc2x0 C. and 0xc2x0 C., followed by deprotection to yield compounds of formula I where R1 is substituted with (R2)OR2.
Referring to Scheme 7, compounds of formula (31) can be formed under conditions well known to those skilled in the art. Treatment of compounds (6) or (8) with an amine, such as piperidine, in a suitable solvent (e.g., dichloroethane) and a reducing agent such as sodium triacetoxyborohydride, followed by deprotection will yield compounds of formula I where R1 is substituted with a nitrogen-containing heterocycle.
Referring to Scheme 8, compounds of general formula (33) can be obtained using conventional methods. For example, the reaction of compounds of formula (2) with n-butyllithium in the presence of N,N,Nxe2x80x2,Nxe2x80x2-tetramethylethylenediamine in a suitable solvent such as tetrahydrofuran, followed by quenching with ketone (32) (commercially available from Aldrich), and hydrolysing with aqueous acid, can yield compounds of formula (33). Functional group manipulation as outlined in Schemes 1-7 and Scheme 8 then allows the synthesis of compounds of formula 1.
Referring to scheme 9, compounds of formula (15), (6) or (8) can be further derivatised to yield compounds of formula (34) using standard Wittig or Wadworths-Emmons chemistry, followed by suitable deprotection. Compounds of formula (34) can be reduced using standard hydrogenation as described above to yield compounds where Y is OH, O-alkyl, or an aminoalkyl. Standard Wadworths-Emmons chemistry can also yield compounds of formula (35). Reduction under suitable conditions will yield compounds of formula (36), which can be further derivatised using standard chemistry described previously in this document to give compounds where NYIYII is an amide, sulfonamide, or aminoalkyl.
Referring to Scheme 10, compounds of formula (10) can be converted into compounds of formula (37) using standard alkylation procedures. For example, compound (10) can be treated with a suitable base such as lithium diisopropyl amide in a suitable solvent such as tetrahydrofuran at a temperature between xe2x88x9278xc2x0 C. and 0xc2x0 C., followed by the addition of a suitable alkylating agent. Such alkylating agents are well known to those of skill in the art, and can include chloro, bromo, or iodoalkyl compounds; epoxides; aldehydes; aziridines; xcex1,xcex2-unsaturated esters, ketones or amides; acyl chlorides; electrophilic sources of oxygen such as Mo(CO)5pyridine (Crimmons, M. T. et al., 1992, J. Am. Chem. Soc., 114:5445); or electrophilic sources of nitrogen such as 2,4,6-triisopropylbenzene sulfonyl azide (Evans, P. A. et al., 1992, Tetrahedron Lett. 33:6959). Such alkylating reagents are commercially available or can be prepared by standard procedures well known to those of skill in the art.
Compounds of formula (37) can be further manipulated using methodology similar to that described above. For instance, alkylation of compounds of formula (37) under conditions of kinetic deprotonation (see, e.g., Kopka, I. and Rathke, M. W., 1981, J. Org. Chem. 46:3771), followed by alkylation as previously described, would yield compounds of formula (38). Alternatively, alkylation of compounds of formula (37) under conditions of thermodynamic deprotonation (Kopka and Rathke, 1981, above), followed by alkylation as previously described, would yield compounds of formula (45). Further alkylation or functional group manipulation known to those of skill in the art and, as described elsewhere in this document, followed by removal of the carbonyl protecting group under standard conditions, e.g., aqueous hydrochloric acid at about 0xc2x0 C. to 50xc2x0 C., would yield compounds of formulae (40), (46), and (49).
Compounds of formula (37) can also be protected with a suitable protecting group, e.g., ethylenedithio ketal, and after removal of the ketal protecting group under standard reaction conditions, e.g., aqueous hydrochloric acid at about 0xc2x0 C. to 50xc2x0 C., would allow further functionalisation of the cycloalkyl ring using the methodology described above to yield compounds of formula (44).
Referring to Scheme 11, compounds of formula (50) can be formed from compounds of formula (10) using known methodology (see, e.g., Adam, W. et al., 1989, Tetrahedron Lett. 30:6497) (Ts=tosyl). Standard functional group manipulation yields compounds of formula (55) and (57). Oxirane ring cleavage by an amine yields compounds of formula (51). Alternatively, acid hydrolysis yields compounds of formula (52). Conversion of the corresponding alcohol to a leaving group such as para-toluenesulfonyl would allow the nucleophilic displacement with a range of nucleophiles under standard, well-known conditions. Such nucleophiles may include amines, thiolates, alkoxides, and carbon-based nucleophiles such as cyanide, which are commercially available or prepared by standard procedures well known to those of skill in the art.
Compounds of formula (40), (44) and (49) can be prepared using the above-described methods or other methods known in the art such that substituents on R1 are as defined above.
Referring to Schemes 10 and 11, ketones of formulae (37), (38), (40), (42), (43), (44), (45), (46), (47), (49), (51), (54), (55), and (57) can be further manipulated as described in Schemes 1-9 above, and converted into compounds of formula I as described in Schemes 2 and 3.
Referring to Scheme 12, compounds of formula I can also be prepared using the methodology described above. Compounds of formula (58) can be converted into compounds of formula I using the chemistry as described in Schemes 1-11 above.
It will be appreciated by those of skill in the art that in the processes described above, the functional groups of intermediate compounds may need to be protected by protecting groups. The use of protecting groups is well-known in the art, and is fully described, among other places, in: Protecting Groups in Organic Chemistry, J. W. F. McOmie, (ed.), 1973, Plenum Press; and in: Protecting Groups in Organic Synthesis, 2nd edition, T. W. Greene and P. G. M. Wutz, 1991, Wiley-Interscience, which are incorporated by reference in their entirety.
The compounds of the present invention can also synthesized by application of alternative synthetic routes, such as those described in European Patent Application No. EP 1134207 A1 by Pfizer Products Inc, published Sep. 19, 2001.
The compounds of formula I that are basic in nature are capable of forming a wide variety of different salts with various inorganic and organic acids. Although such salts must be pharmaceutically acceptable for administration to animals, it is often desirable in practice to initially isolate a compound of formula I from the reaction mixture as a pharmaceutically unacceptable salt and then simply convert the latter back to the free base compound by treatment with an alkaline reagent and subsequently convert the latter free base to a pharmaceutically acceptable acid addition salt. The acid addition salts of the active base compounds of this invention are readily prepared by treating the base compound with a substantially equivalent amount of the chosen mineral or organic acid in an aqueous solvent medium or in a suitable organic solvent, such as methanol or ethanol. Upon careful evaporation of the solvent, the desired solid salt is readily obtained.
Those compounds of formula I that are acidic in nature are capable of forming base salts with various pharmaceutically acceptable cations. Examples of such salts include the alkali metal and alkaline earth metal salts and, particularly, the sodium and potassium salts. These salts can be prepared by conventional techniques. The chemical bases that are used as reagents to prepare the pharmaceutically acceptable base salts of this invention are those that form non-toxic base salts with the acidic compounds of formula I. Such non-toxic base salts include those derived from such pharmaceutically acceptable cations as sodium, potassium, calcium and magnesium, etc. These salts can easily be prepared by treating the corresponding acidic compounds with an aqueous solution containing the desired pharmaceutically acceptable cations, and then evaporating the resulting solution to dryness, preferably under reduced pressure. Alternatively, they can also be prepared by mixing lower alkanolic solutions of the acidic compounds and the desired alkali metal alkoxide together, and then evaporating the resulting solution to dryness, as described above. In either case, stoichiometric quantities of reagents are preferably employed in order to ensure completeness of reaction and maximum yields of the desired final products.
Compounds of formula I and their pharmaceutically acceptable salts (hereinafter xe2x80x9cthe active compounds used in this inventionxe2x80x9d) are useful in the treatment of disorders of human pigmentation, including solar and simple lentigines (including age/liver spots), melasma/chloasma and postinflammatory hyperpigmentation. Such compounds reduce skin melanin levels by inhibiting the production of melanin, whether the latter is produced constitutively or in response to UV irradiation (such as sun exposure). Thus, the active compounds used in this invention can be used to reduce skin melanin content in non-pathological states so as to induce a lighter skin tone, as desired by the user, or to prevent melanin accumulation in skin that has been exposed to UV irradiation. They can also be used in combination with skin peeling agents (including glycolic acid or trichloroacetic acid face peels) to lighten skin tone and prevent repigmentation. The appropriate dose regimen, the amount of each dose administered, and specific intervals between doses of the active compound will depend upon the particular active compound employed, the condition of the patient being treated, and the nature and severity of the disorder or condition being treated. Preferably, the active compound is administered in an amount and at an interval that results in the desired treatment of or improvement in the disorder or condition being treated.
An active compound used in the present invention can also be used in combination with sun screens (UVA or UVB blockers) to prevent repigmentation, to protect against sun or UV-induced skin darkening or to enhance their ability to reduce skin melanin and their skin bleaching action. An active compound used in the present invention can also be used in combination with retinoic acid or its derivatives or any compounds that interact with retinoic acid receptors and accelerate or enhance the invention""s ability to reduce skin melanin and skin bleaching action, or enhance the invention""s ability to prevent the accumulation of skin melanin. An active compound used in the present invention can also be used in combination with 4-hydroxyanisole.
The active compounds used in this invention can also be used in combination with ascorbic acid, its derivatives and ascorbic-acid based products (such as magnesium ascorbate) or other products with an anti-oxidant mechanism (such as resveratrol) which accelerate or enhance their ability to reduce skin melanin and their skin bleaching action.
Occurrences in the skin or hair of noticeable but undesired pigmentation as a result of melanin production, overproduction or underproduction can be treated using the methods of the present invention. Cosmetic applications for methods of the present invention include the topical application of compositions containing one or more of the compounds of the present invention to enhance or otherwise alter the visual appearance of skin or hair. The cosmetic compositions of the present invention are also useful to provide a smoother or softer skin appearance or texture.
As one skilled in the art would know in view of this disclosure, an active compound used in the methods of the present invention may be used alone or in combination with other compounds known in the art to affect melanin synthesis, particularly other melanin synthesis inhibitors, including tyrosinase inhibitors. Such inhibitors include those currently known in the art and those to be developed in the future. Known inhibitors include various resorcinol derivatives, kojic acid derivatives, hydroquinone, melamine, and various types of plant extracts, among others. For example, any of the compounds used according to a skin-lightening method of the present invention may be used in combination with a tyrosinase inhibitor or other skin-whitening agent, including any one or more of those agents, including compounds or extracts, described in the following patent publications: U.S. Pat. No. 4,278,656 to Nagai et al, issued Jul. 14, 1981, describing the use of kojic acid and its derivatives; U.S. Pat. No. 4,369,174 to Nagai et al., issued Jan. 18, 1983, describing the use of kojic acid and its derivatives; U.S. Pat. No. 4,959,393 to Torihara et al., issued Sep. 25, 1990, describing the use of 4-n-butylresorcinol, 4-isoamyl resorcinol and other resorcinol derivatives; U.S. Pat. No. 5,580,549 to Fukuda et al., issued Dec. 3, 1996, describing the use of various hydroxybenzoic acid derivatives; U.S. Pat. No. 6,123,959 to Jones et al., issued Sep. 26, 2000, describing the use of liposomes containing combinations of competitive inhibitors, such as arbutin, and non-competitive inhibitors, such as aloesin, of melanin synthesis; U.S. Pat. No. 6,132,740 to Hu, issued Oct. 17, 2000, describing the use of various resorcinol derivatives; U.S. Pat. No. 6,159,482 to Tuloup et a al., issued Dec. 12, 2000, describing the use of various hydroxyphenyl oxamate derivatives; WO 99/32077 by L""Oreal, published Jul. 1, 1999, describing the use of various phenolic amides; WO 99/64025 by Fytokem Prod. Inc., published Dec. 16, 1999, describing the use of various dicotyledonous plant extracts; WO 00/56702 by Pfizer Inc., published Sep. 28, 2000 describing various resorcinol derivatives; WO 00/76473 by Shiseido Co. Ltd., published Dec. 12, 2000, describing the use of Withania plant extracts; EP 997140 by L""Oreal SA, published May 3, 2000, describing the use of combinations of mulberry and skullcap extracts with salicylic acid derivatives; JP 5221846 by Kunimasa Tomoji, published Aug. 31, 1993, describing the use of kojic acid derivatives; JP 7242687 by Shiseido Co. Ltd., published Sep. 19, 1995, describing the use of Trichoderma extracts; JP 7324023 by Itogawa H, published Dec. 12, 1995, describing the use of Pseudostellariae radix extracts; JP 8012552 by Shiseido Co. Ltd., published Jan. 16, 1996, describing the use of Amor seco extracts; JP 8012554 by Shiseido Co. Ltd., published Jan. 16, 1996, describing the use of Jabonciilo extracts; JP 8012557 by Shiseido Co. Ltd., published Jan. 16, 1996, describing the use of Huaca extracts; JP 8012560 by Shiseido Co. Ltd., published Jan. 16, 1996, describing the use of Copaiba extracts; JP 8012561 by Shiseido Co. Ltd., published Jan. 16, 1996, describing the use of Arnica extracts; JP 8134090 by Fujisawa, published May 28, 1996, describing the use of galactosyl-kojic acid derivatives; JP 8168378 by Kirinjo KK, published Jul. 2, 1996, describing the use of lees from rice wine production; JP 8277225 by Kansai Koso KK, published Oct. 22, 1996, describing the use of Autocarpus incisus extracts; JP 9002967 by Sanki Shoji KK, published Jan. 7, 1997, describing the use of Prunus domesticus extracts; JP 9295927 by Yagi Akira, published Nov. 18, 1997, describing the use of Aloe vera extracts; JP 10072330 by Kansai Kouso, published Mar. 17, 1998, describing the use of oxydesberatrol derivatives; JP 10081626 by Kamiyama KK, published Mar. 31, 1998, describing the use of 4-substituted benzoic acids; JP 10101543 by Kansai Kouso KK, published Apr. 21, 1998, describing the use of flavonoids; JP 11071231 by Maruzen Pharm., published Mar. 16, 1999, describing the use of bakuchiol; JP 11079934 by Kyodo Nyugyo, published Mar. 23, 1999, describing the use of low molecular weight thiol from sake lees; JP 11246347 by Shiseido Co. Ltd., published Sep. 14, 1999, describing the use of Achillea millefolium extracts; JP 11246344 by Shiseido Co. Ltd., published Sep. 14, 1999, describing the use of Gliricidia extracts; JP 2000-080023 by Kanebo Ltd., published Mar. 21, 2000, describing the use of metallothionine inducers; JP 2000-095663 by Kose KK, published Apr. 4, 2000, describing the use of various plant extracts; JP 2000-159681 by Hai Tai Confectionary Co. Ltd., published Jun. 13, 2000, describing the use of grape seed extract; JP-7206753 by Nikken Food KK, published Aug. 8, 1995, describing the use of dihydroxycurcumin derivatives; JP-5320025 by Kunimasa T, published Dec. 3, 1993, describing the use of kojic acid derivatives; and JP-59157009 by Yakurigaku Chuou K E, published Sep. 6, 1984, describing the use of P-thujaplicin, hydroquinone or a pyrone compound in combination with a melanin adsorbent; among others; which patent publications are incorporated herein by reference in their entireties.
This invention relates both to methods of lightening or reducing the pigmentation of skin in which the compound of formula I, or pharmaceutically acceptable salt thereof, and one or more of the other active ingredients referred to above are administered together, as part of the same pharmaceutical composition, as well as methods in which they are administered separately as part of an appropriate dose regimen designed to obtain the benefits of the combination therapy. The appropriate dose regimen, the amount of each dose administered, and specific intervals between doses of each active agent will depend upon the specific combination of active agents employed, the condition of the patient being treated, and the nature and severity of the disorder or condition being treated. Such additional active ingredients will generally be administered in amounts less than or equal to those for which they are effective as single topical therapeutic agents. The FDA approved dosages for such active agents that have received FDA approval for administration to humans are publicly available.
The active compounds of the present invention are generally administered in the form of pharmaceutical compositions comprising at least one of the compounds of formula (I), together with a pharmaceutically acceptable vehicle or diluent. Alternatively, an active compound of this invention can be administered in the form of a cosmetic composition comprising at least one compound of formula (I), together with a cosmetically acceptable vehicle or diluent. Such compositions are generally formulated in a conventional manner utilizing solid or liquid vehicles or diluents as appropriate for topical administration, in the form of solutions, gels, creams, jellies, pastes, lotions, ointments, salves, aerosols and the like.
Examples of vehicles for application of the active compounds of this invention include an aqueous or water-alcohol solution, an emulsion of the oil-in-water or water-in-oil type, an emulsified gel, or a two-phase system. Preferably, the compositions according to the invention are in the form of lotions, creams, milks, gels, masks, microspheres or nanospheres, or vesicular dispersions. In the case of vesicular dispersions, the lipids of which the vesicles are made can be of the ionic or nonionic type, or a mixture thereof. Such vehicles can include suitable viscosity enhancing agents, pH adjusting agents, stabilizers, fragrances, etc., as known in the art of topical formulations.
An effective dosage and treatment protocol can be determined by conventional means, starting with a low dose in laboratory animals and then increasing the dosage while monitoring the effects, and systematically varying the dosage regimen as well. Animal studies, preferably mammalian studies, are commonly used to determine the maximal tolerable dose, or MTD, of a bioactive agent per kilogram weight. Those skilled in the art can a extrapolate doses for efficacy and avoidance of toxicity to other species, including humans.
Before human studies of efficacy are undertaken, Phase I clinical studies in normal subjects can help establish safe doses. Numerous factors can be taken into consideration by a clinician when determining an optimal dosage for a given subject. Primary among these is the toxicity and half-life of the chosen compound. Additional factors include the size of the patient, the age of the patient, the general condition of the patient, the particular disease, condition, or disorder being treated, the severity of the disease, condition, or disorder being treated, the presence of other drugs in the patient, the effect desired, and the like. The trial dosages would be chosen after consideration of the results of animal studies and the clinical literature.
One of ordinary skill in the art will appreciate that the endpoint of treatment chosen in a particular case will vary according to the disease, condition, or disorder being treated, the outcome desired by the patient, subject, or treating physician, and other factors. Where the composition is being used to lighten skin color such as, for example, to reverse hyperpigmentation caused by, for example, inflammation or diseases such as melasma, or to lighten hair color, any one of a number of endpoints can be chosen. For example, endpoints can be defined subjectively such as, for example, when the subject is simply xe2x80x9csatisfiedxe2x80x9d with the results of the treatment. For pharmacological compositions, the endpoint can be determined by the patient""s, or the treating physician""s, satisfaction with the results of the treatment. Alternatively, endpoints can be defined objectively. For example, the patient""s or subject""s skin or hair in the treated area can be compared to a color chart. Treatment is terminated when the color of the skin or hair in the treated area is similar in appearance to a color on the chart. Alternatively, the reflectance of the treated skin or hair can be measured, and treatment can be terminated when the treated skin or hair attains a specified reflectance. Alternatively, the melanin content of the treated hair or skin can be measured. Treatment can be terminated when the melanin content of the treated hair or skin reaches a specified value. Melanin content can be determined in any way known to the art, including by histological methods, with or without enhancement by stains for melanin.
In the depigmenting compositions according to the present invention, the concentration of the active compound of the invention is generally between 0.01 and 10%, preferably between 0.1 and 10%, relative to the total weight of the composition.
The compositions of this invention can optionally also contain a moistener, a surfactant, keratolytic, an anti-inflammatory agent, a complexing agent, an antioxidant, a preservative, a colorant, a fragrance, or a sunscreen.
The compositions of the present invention can be applied directly to the skin. Alternatively, they can be delivered by various transdermal drug delivery systems, such as transdermal patches as known in the art. For example, for topical administration, the active ingredient can be formulated in a solution, gel, lotion, ointment, cream, suspension, paste, liniment, powder, tincture, aerosol, patch, or the like in a pharmaceutically or cosmetically acceptable form by methods well known in the art. The composition can be any of a variety of forms common in the pharmaceutical or cosmetic arts for topical application to animals or humans, including solutions, lotions, sprays, creams, ointments, salves, gels, etc., as described below. Preferred agents are those that are viscous enough to remain on the treated area, those that do not readily evaporate, and/or those that are easily removed by rinsing with water, optionally with the aid of soaps, cleansers and/or shampoos. Actual methods for preparing topical formulations are known or apparent to those skilled in the art, and are described in detail in Remington""s Pharmaceutical Sciences, 1990 (supra); and Pharmaceutical Dosage Forms and Drug Delivery Systems, 6th ed., Williams and Wilkins (1995).
In order to enhance the percutaneous absorption of the active ingredients, one or more of a number of agents can be added in the topical formulations including, but not limited to, dimethylsulfoxide, dimethylacetamide, dimethylformamide, surfactants, azone, alcohol, acetone, propylene glycol and polyethylene glycol. In addition, physical methods can also be used to enhance transdermal penetration such as, e.g., by iontophoresis or sonophoresis. Alternatively, or in addition, liposomes may be employed.
A topically applied composition of the invention contains a pharmaceutically effective agent that lightens skin as described herein, and those ingredients as are necessary for use as a carrier, such as an emulsion, a cream, an ointment, an aqueous solution, a lotion or an aerosol. Non-limiting examples of such carriers are described in more detail below and may be found in International Patent Publication WO 00/62742, published Oct. 26, 2000; U.S. Pat. No. 5,691,380 to Mason et al., issued Nov. 25, 1997; U.S. Pat. No. 5, 968,528 to Deckner et al., issued Oct. 19, 1999; U.S. Pat. No. 4,139,619 to Chidsey, III, issued Feb. 13, 1979; and U.S. Pat. No. 4,684,635 to Orentreich et al., issued Aug. 4, 1987; which are incorporated herein by reference. Suitable pharmaceutical carriers are further described in Remington""s Pharmaceutical Sciences, 17th ed., Mack Publishing Company, Easton, Pa. (1990), which is a standard reference text in this field.
The pharmaceutical compositions of the invention may optionally include components suitable for application to keratinous tissue, that is, when incorporated into the composition, they are suitable for use in contact with human keratinous tissue without undue toxicity, incompatibility, instability, allergic response, and the like within the scope of sound medical judgment. In addition, such optional components are useful provided that they do not unacceptably alter the benefits of the active compounds of the invention. The CTFA Cosmetic Ingredient Handbook, Second Edition (1992) describes a wide variety of non-limiting cosmetic and pharmaceutical ingredients commonly used in the skin care industry, which are suitable for use in the compositions of the present invention. Examples of these ingredient classes include: abrasives, absorbents, aesthetic components such as fragrances, pigments, colorings/colorants, essential oils, skin sensates, astringents, etc. (e.g., clove oil, menthol, camphor, eucalyptus oil, eugenol, menthyl lactate, witch hazel distillate), anti-acne agents, anti-caking agents, antifoaming agents, antimicrobial agents (e.g., iodopropyl butylcarbamate), antioxidants, binders, biological additives, buffering agents, bulking agents, chelating agents, chemical additives, colorants, cosmetic astringents, cosmetic biocides, denaturants, drug astringents, external analgesics, film formers or materials, e.g., polymers, for aiding the film-forming properties and substantivity of the composition (e.g., copolymer of eicosene and vinyl pyrrolidone), opacifying agents, pH adjusters, propellants, reducing agents, sequestrants, skin-conditioning agents (e.g., humectants, including miscellaneous and occlusive), skin soothing and/or healing agents (e.g., panthenol and derivatives (e.g., ethyl panthenol), aloe vera, pantothenic acid and its derivatives, allantoin and bisabolol and dipotassium glycyrrhizinate), skin treating agents, thickeners, and vitamins and derivatives thereof.
In addition to the pharmaceutically effective amount of an agent disclosed herein, the topical compositions of the present invention also comprise a dermatologically acceptable carrier. The phrase xe2x80x9cdermatologically acceptable carrierxe2x80x9d, as used herein, means that the carrier is suitable for topical application to the skin, i.e., keratinous tissue, has good aesthetic properties, is compatible with the active agents of the present invention and any other components, and will not cause any safety or toxicity concerns. A safe and effective amount of carrier is from about 50% to about 99.99%, preferably from about 80% to about 99.9%, more preferably from about 90% to about 98%, and most preferably from about 90% to about 95% of the composition.
The carrier utilized in the compositions of the invention can be in a wide variety of forms. These include emulsion carriers, including, but not limited to, oil-in-water, water-in-oil, water-in-oil-in-water, and oil-in-water-in-silicone emulsions, a cream, an ointment, an aqueous solution, a lotion or an aerosol. As will be understood by the skilled artisan, a given component will distribute primarily into either the water or oil/silicone phase, depending on the water solubility/dispersibility of the component in the composition.
Emulsions according to the present invention generally contain a pharmaceutically effective amount of an agent disclosed herein and a lipid or oil. Lipids and oils may be derived from animals, plants, or petroleum and may be natural or synthetic (i.e., man-made). Preferred emulsions also contain a humectant, such as glycerin. Emulsions will preferably further contain from about 1% to about 10%, more preferably from about 2% to about 5%, of an emulsifier, based on the weight of the carrier. Emulsifiers may be nonionic, anionic or cationic. Suitable emulsifiers are described in, for example, U.S. Pat. No. 3,755,560 to Dickert et al., issued Aug. 28, 1973; U.S. Pat. No. 4,421,769 to Dixon, et al., issued Dec. 20, 1983; and McCutcheon""s Detergents and Emulsifiers, North American Edition, pages 317-324 (1986).
The emulsion may also contain an anti-foaming agent to minimize foaming upon application to the keratinous tissue. Anti-foaming agents include high molecular weight silicones and other materials well known in the art for such use.
Suitable emulsions may have a wide range of viscosities, depending on the desired product form. Exemplary low viscosity emulsions, which are preferred, have a viscosity of about 50 centistokes or less, more preferably about 10 centistokes or less, most preferably about 5 centistokes or less. The emulsion may also contain an anti-foaming agent to minimize foaming upon application to the keratinous tissue. Anti-foaming agents include high molecular weight silicones and other materials well known in the art for such use.
One type of emulsion is a water-in-silicone emulsion. Water-in-silicone emulsions contain a continuous silicone phase and a dispersed aqueous phase. Preferred water-in-silicone emulsions of the present invention comprise from about 1% to about 60%, preferably from about 5% to about 40%, more preferably from about 10% to about 20%, by weight of a continuous silicone phase. The continuous silicone phase exists as an external phase that contains or surrounds the discontinuous aqueous phase described hereinafter.
The continuous silicone phase may contain a polyorganosiloxane oil. A preferred water-in-silicone emulsion system is formulated to provide an oxidatively stable vehicle for delivery of a pharmaceutically effective amount of an agent disclosed herein. The continuous silicone phase of these preferred emulsions comprises between about 50% and about 99.9% by weight of organopolysiloxane oil and less than about 50% by weight of a non-silicone oil. In an especially preferred embodiment, the continuous silicone phase comprises at least about 50%, preferably from about 60% to about 99.9%, more preferably from about 70% to about 99.9%, and even more preferably from about 80% to about 99.9%, polyorganosiloxane oil by weight of the continuous silicone phase, and up to about 50% non-silicone oils, preferably less than about 40%, more preferably less than about 30%, even more preferably less than about 10%, and most preferably less than about 2%, by weight of the continuous silicone phase. These useful emulsion systems may provide more oxidative stability over extended periods of time than comparable water-in-oil emulsions containing lower concentrations of the polyorganosiloxane oil. Concentrations of non-silicone oils in the continuous silicone phase are minimized or avoided altogether so as to possibly further enhance oxidative stability of the active compound of the invention in the compositions. Water-in-silicone emulsions of this type are described in U.S. Pat. No. 5,691,380 to Mason et al., issued Nov. 25, 1997.
The organopolysiloxane oil for use in the composition may be volatile, non-volatile, or a mixture of volatile and non-volatile silicones. The term xe2x80x9cnonvolatilexe2x80x9d as used in this context refers to those silicones that are liquid under ambient conditions and have a flash point (under one atmospheric of pressure) of or greater than about 100 degrees Celsius. The term xe2x80x9cvolatilexe2x80x9d as used in this context refers to all other silicone oils. Suitable organopolysiloxanes can be selected from a wide variety of silicones spanning a broad range of volatilities and viscosities. Examples of suitable organopolysiloxane oils include polyalkylsiloxanes, cyclic polyalkylsiloxanes, and polyalkylarylsiloxanes, which are known to those skilled in the art and commercially available.
The continuous silicone phase may contain one or more non-silicone oils. Concentrations of non-silicone oils in the continuous silicone phase are preferably minimized or avoided altogether so as to further enhance oxidative stability of the pharmaceutically effective agent in the compositions. Suitable non-silicone oils have a melting point of about 25xc2x0 C. or less under about one atmosphere of pressure. Examples of non-silicone oils suitable for use in the continuous silicone phase are those well known in the chemical arts in topical personal care products in the form of water-in-oil emulsions, e.g. mineral oil, vegetable oils, synthetic oils, semisynthetic oils, etc.
Useful topical compositions of the present invention comprise from about 30% to about 90%, more preferably from about 50% to about 85%, and most preferably from about 70% to about 80% of a dispersed aqueous phase. In emulsion technology, the term xe2x80x9cdispersed phasexe2x80x9d is a term well-known to one skilled in the art which means that the phase exists as small particles or droplets that are suspended in and surrounded by a continuous phase. The dispersed phase is also known as the internal or discontinuous phase. The dispersed aqueous phase is a dispersion of small aqueous particles or droplets suspended in and surrounded by the continuous silicone phase described hereinbefore. The aqueous phase can be water, or a combination of water and one or more water soluble or dispersible ingredients. Non-limiting examples of such optional ingredients include thickeners, acids, bases, salts, chelants, gums, water-soluble or dispersible alcohols and polyols, buffers, preservatives, sunscreening agents, colorings, and the like.
The topical compositions of the present invention typically comprise from about 25% to about 90%, preferably from about 40% to about 80%, more preferably from about 60% to about 80%, water in the dispersed aqueous phase by weight of the composition.
The water-in-silicone emulsions of the present invention preferably comprise an emulsifier. In a preferred embodiment, the composition contains from about 0.1% to about 10% emulsifier, more preferably from about 0.5% to about 7.5%, most preferably from about 1% to about 5%, emulsifier by weight of the composition. The emulsifier helps disperse and suspend the aqueous phase within the continuous silicone phase.
A wide variety of emulsifying agents can be employed herein to form the preferred water-in-silicone emulsion. Known or conventional emulsifying agents can be used in the composition, provided that the selected emulsifying agent is chemically and physically compatible with essential components of the composition, and provides the desired dispersion characteristics. Suitable emulsifiers include silicone emulsifiers, e.g., organically modified organopolysiloxanes, also known to those skilled in the art as silicone surfactants, non-silicon-containing emulsifiers, and mixtures thereof, known by those skilled in the art for use in topical personal care products.
Useful emulsifiers include a wide variety of silicone emulsifiers. These silicone emulsifiers are typically organically modified organopolysiloxanes, also known to those skilled in the art as silicone surfactants. Suitable emulsifiers are described, for example, in McCutcheon""s, Detergents and Emulsifiers, North American Edition (1986), published by Allured Publishing Corporation; U.S. Pat. No. 5,011,681 to Ciotti et al., issued Apr. 30, 1991; U.S. Pat. No. 4,421,769 to Dixon et al., issued Dec. 20, 1983; and U.S. Pat. No. 3,755,560 to Dickert et al., issued Aug. 28, 1973.
Other preferred topical carriers include oil-in-water emulsions, having a continuous aqueous phase and a hydrophobic, water-insoluble phase (xe2x80x9coil phasexe2x80x9d) dispersed therein. Examples of suitable carriers comprising oil-in-water emulsions are described in U.S. Pat. No. 5,073,371 to Turner et al., issued Dec. 17, 1991; and U.S. Pat. No. 5,073,372, to Turner et al., issued Dec. 17, 1991. An especially preferred oil-in-water emulsion, containing a structuring agent, hydrophilic surfactant and water, is described in detail hereinafter.
A preferred oil-in-water emulsion comprises a structuring agent to assist in the formation of a liquid crystalline gel network structure. Without being limited by theory, it is believed that the structuring agent assists in providing Theological characteristics to the composition which contribute to the stability of the composition. The structuring agent may also function as an emulsifier or surfactant. Preferred compositions of this invention comprise from about 0.5% to about 20%, more preferably from about 1% to about 10%, most preferably from about 1% to about 5%, by weight of the composition, of a structuring agent. The preferred structuring agents of the present invention are selected from the group consisting of stearic acid, palmitic acid, stearyl alcohol, cetyl alcohol, behenyl alcohol, stearic acid, palmitic acid, the polyethylene glycol ether of stearyl alcohol having an average of about 1 to about 21 ethylene oxide units, the polyethylene glycol ether of cetyl alcohol having an average of about 1 to about 5 ethylene oxide units, and mixtures thereof.
The preferred oil-in-water emulsions comprise from about 0.05% to about 10%, preferably from about 1% to about 6%, and more preferably from about 1% to about 3% of at least one hydrophilic surfactant which can disperse the hydrophobic materials in the water phase (percentages by weight of the topical carrier). The surfactant, at a minimum, must be hydrophilic enough to disperse in water. Suitable surfactants include any of a wide variety of known cationic, anionic, zwitterionic, and amphoteric surfactants. See McCutcheon""s. Detergents and Emulsifiers (1986), supra; U.S. Pat. No. 5,011,681 to Ciotti et al., issued Apr. 30, 1991; U.S. Pat. No. 4,421,769 to Dixon et al. issued Dec. 20, 1983; and U.S. Pat. No. 3,755,560 to Dickert et al., issued Aug. 28, 1973. The exact surfactant chosen depends upon the pH of the composition and the other components present. Preferred are cationic surfactants, especially dialkyl quaternary ammonium compounds, examples of which are described in U.S. Pat. No. 5,151,209 to McCall et al. issued Sep. 29, 1992; U.S. Pat. No. 5,151,210 to Steuri et al. issued Sep. 29, 1992; U.S. Pat. No. 5,120,532 to Wells et al, issued Jun. 9, 1992; U.S. Pat. No. 4,387,090 to Bolich Jr., issued Jun. 7, 1983; U.S. Pat. No. 3,155,591 to Hilfer, issued Nov. 3, 1964; U.S. Pat. No. 3,929,678 to Laughlin et al, issued Dec. 30, 1975; U.S. Pat. No. 3,959,461 to Bailey et al., May 25, 1976; McCutcheon""s, Detergents and Emulsifiers (North American edition 1979) M.C. Publishing Co.; and Schwartz, et al., Surface Active Agents, Their Chemistry and Technology, New York: Interscience Publishers, 1949.
Alternatively, other useful cationic emulsifiers include amino-amides. Non-limiting examples of these cationic emulsifiers include stearamidopropyl PG-dimonium chloride phosphate, behenamidopropyl PG dimonium chloride, stearamidopropyl ethyldimonium ethosulfate, stearamidopropyl dimethyl (myristyl acetate) ammonium chloride, stearamidopropyl dimethyl cetearyl ammonium tosylate, stearamidopropyl dimethyl ammonium chloride, stearamidopropyl dimethyl ammonium lactate, and mixtures thereof.
A wide variety of anionic surfactants are also useful herein. See, e.g., U.S. Pat. No. 3,929,678, to Laughlin et al., issued Dec. 30, 1975. In addition, amphoteric and zwitterionic surfactants are also useful herein.
The preferred oil-in-water emulsion comprises from about 25% to about 98%, preferably from about 65% to about 95%, more preferably from about 70% to about 90% water by weight of the topical carrier.
The hydrophobic phase is dispersed in the continuous aqueous phase. The hydrophobic phase may contain water-insoluble or partially soluble materials such as are known in the art, including but not limited to the silicones described herein in reference to silicone-in-water emulsions, and other oils and lipids such as described above in reference to emulsions.
The topical compositions of the subject invention, including but not limited to lotions and creams, may comprise a dermatologically acceptable emollient. Such compositions preferably contain from about 2% to about 50% of the emollient. As used herein, xe2x80x9cemollientxe2x80x9d refers to a material useful for the prevention or relief of dryness, as well as for the protection of the skin. A wide variety of suitable emollients are known and may be used herein. See, e.g., Sagarin, Cosmetics, Science and Technology, 2nd Edition, Vol. 1, pp. 3243 (1972), which contains numerous examples of materials suitable as an emollient. A preferred emollient is glycerin. Glycerin is preferably used in an amount of from or about 0.001 to or about 20%, more preferably from or about 0.01 to or about 10%, most preferably from or about 0.1 to or about 5%, e.g., 3%.
Lotions and creams according to the present invention generally comprise a solution carrier system and one or more emollients. Lotions typically comprise from about 1% to about 20%, preferably from about 5% to about 10% of emollient; from about 50% to about 90%, preferably from about 60% to about 80% water; and a pharmaceutically effective amount of an agent described herein. A cream typically comprises from about 5% to about 50%, preferably from about 10% to about 20% of emollient; from about 45% to about 85%, preferably from about 50% to about 75% water; and a pharmaceutically effective amount of an agent described herein.
Ointments of the present invention may comprise a simple carrier base of animal or vegetable oils or semi-solid hydrocarbons (oleaginous); absorption ointment bases, which absorb water to form emulsions; or water soluble carriers, e.g., a water soluble solution carrier. Ointments may further comprise a thickening agent, such as described in Sagarin, Cosmetics, Science and Technology, 2nd Edition, Vol. 1, pp. 72-73 (1972), incorporated herein by reference, and/or an emollient. For example, an ointment may comprise from about 2% to about 10% of an emollient; from about 0.1% to about 2% of a thickening agent; and a pharmaceutically effective amount of an agent described herein.
By way of non-limiting example, 1000 g of topical cream is prepared from the following types and amounts of ingredients: a pharmaceutically effective amount of an agent disclosed herein, tegacid regular (150 g) (a self-emulsifying glyceryl monostearate from Goldschmidt Chemical Corporation, New York, N.Y.), polysorbate 80 (50 g), spermaceti (100 g), propylene glycol (50 g), methylparaben (1 g), and deionized water in sufficient quantity to reach 1000 gm. The tegacid and spermaceti are melted together at a temperature of 70-80xc2x0 C. The methylparaben is dissolved in about 500 g. of water and the propylene glycol, polysorbate 80, and active compound are added in turn, maintaining a temperature of 75-800 C. The methylparaben mixture is added slowly to the tegacid and spermaceti melt, with constant stirring. The addition is continued for at least 30 minutes with additional stirring until the temperature has dropped to 40-45xc2x0 C. Finally, sufficient water is added to bring the final weight to 1000 g. and the preparation stirred to maintain homogeneity until cooled and congealed.
By way of non-limiting example, 1000 g of a topical ointment is prepared from the following types and amounts of ingredients: a pharmaceutically effective amount of an agent disclosed herein, zinc oxide (50 g), calamine (50 g), liquid petrolatum (heavy) (250 g), wool fat (200 g), and enough white petrolatum to reach 1000 g. Briefly, the white petrolatum and wool fat are melted and 100 g of liquid petrolatum added thereto. The pharmaceutically effective amount of an agent disclosed herein, zinc oxide, and calamine are added to the remaining liquid petrolatum and the mixture milled until the powders are finely divided and uniformly dispersed. The mixture is stirred into the white petrolatum, melted and cooled with stirring until the ointment congeals.
By way of non-limiting example, 1000 g of an ointment containing a pharmaceutically effective amount of an agent disclosed herein is prepared from the following types and amounts of ingredients: a pharmaceutically effective amount of an agent disclosed herein, light liquid petrolatum (250 g), wool fat (200 g), and enough white petrolatum to reach 1000 g. Briefly, the pharmaceutically effective amount of an agent disclosed herein is finely divided and added to the light liquid petrolatum. The wool fat and white petrolatum are melted together, strained, and the temperature adjusted to 45-50xc2x0 C. The liquid petrolatum slurry is added, and the ointment stirred until congealed.
By way of non-limiting example, 1000 ml of an aqueous solution containing a pharmaceutically effective amount of an agent disclosed herein is prepared from the following types and amounts of ingredients: a pharmaceutically effective amount of an agent disclosed herein, polyethylene glycol 4000 (120 g) myristyl-gamma-picolinium chloride (0.2 g), polyvinylpyrrolidone (1 g), and enough deionized water to reach 1000 milliliters. Briefly, the ingredients are dissolved in the water and the resulting solution is sterilized by filtration.
By way of non-limiting example, 1000 g of lotion containing a pharmaceutically effective amount of an agent disclosed herein is prepared from the following types and amounts of ingredients: a pharmaceutically effective amount of an agent disclosed herein, N-methyl pyrolidone (40 g), and enough propylene glycol to reach 1000 g.
By way of non-limiting example, an aerosol containing a pharmaceutically effective amount of an agent disclosed herein is prepared from the following types and amounts of materials: a pharmaceutically effective amount of an agent disclosed herein, absolute alcohol (4.37 g), dichlorodifluoroethane (1.43 g) and dichlorotetrafluoroethane (5.70 g). Briefly, the pharmaceutically effective amount of an agent disclosed herein is dissolved in the absolute alcohol and the resulting solution filtered to remove particles and lint. This solution is chilled to about minus 30xc2x0 C. Then, to this is added the chilled mixture of dichlorodifluoromethane and dichlorotetrafluoroethane.
For oral administration, gelatin capsules or liquid-filled soft gelatin capsules can contain the active ingredient and powdered or liquid carriers, such as lactose, lecithin starch, cellulose derivatives, magnesium stearate, stearic acid, and the like. Similar diluents can be used to make compressed tablets. Both tablets and capsules can be manufactured as sustained release products to provide for continuous release of medication over a period of hours. Compressed tablets can be sugar-coated or film-coated to mask any unpleasant taste and to protect the tablet from the atmosphere, or enteric-coated for selective, targeted disintegration in the gastrointestinal tract. Liquid dosage forms for oral administration can contain coloring and/or flavoring to increase patient acceptance.
In general, sterile water, oil, saline, aqueous dextrose (glucose), polysorbate and related sugar solutions and glycols such as propylene glycol or polyethylene glycols, are suitable carriers for parenteral solutions. Solutions or emulsions for parenteral administration preferably contain about 5-15% polysorbate 80 or lecithin, suitable stabilizing agents and, if necessary, buffer substances. Anti-oxidizing agents such as, but not limited to, sodium bisulfite, sodium sulfite, or ascorbic acid, either alone or combined, are suitable stabilizing agents. Also useful are citric acid and its salts, and sodium EDTA. In addition, parenteral solutions can contain preservatives including, but not limited to, benzalkonium chloride, methyl- or propyl-paraben, and chlorobutanol.
Additional examples of particular formulations comprising an active compound of the present invention are provided below.
An example of the preparation of a topical gel follows.
The components other than sodium hydroxide are combined to yield a homogeneous dispersion. Addition of sodium hydroxide causes the mixture to gel yielding a ready-to-use semisolid.
An example of the preparation of a topical cream follows.
The first four ingredients are heated to approximately 70xc2x0 C. to produce a uniform melt. The remaining ingredients are combined, heated to approximately 75xc2x0 C., and added with mixing to the previously prepared melt. The emulsion thus formed is subsequently homogenized and cooled to yield a smooth white cream.
An example of the preparation of a topical lotion follows.
The first four ingredients are combined and heated to approximately 70xc2x0 C., then added with agitation to a mixture of the remaining ingredients, also at about 70xc2x0 C. The emulsion is appropriately homogenized and cooled to produce a smooth, white, pourable lotion.
An example of the preparation of a topical solution follows.
All ingredients except sodium hydroxide are combined with agitation, and the pH of the resultant solution is adjusted with 1 N sodium hydroxide, to pH 6, to yield a free-flowing, quick-drying topical solution.
The topical formulations presented herein are examples of typical gel, cream, lotion, or solution dosage forms of active compounds for use in lightening skin. Other optional components can be added or excipient ratios can be adjusted to enhance cosmetic acceptability of the formulations. Additionally, these alterations can be made to customize the composition toward a particular active compound, for example, to ensure solubilization or to enhance chemical or physical stability. Optional components would include viscosity adjusters such as celluloses, emollient oils such as mineral oil or glycerides, humectants such as polyols, cosolvents such as isopropyl alcohol or acetone, emulsifying agents of the anionic, cationic and non-ionic types, preservatives, antioxidants, opacifiers, colorants and perfumes.
An example of the preparation of an oral tablet formulation follows.
The active compound, lactose, and cornstarch (for mix) are blended to uniformity. The cornstarch (for paste) is suspended in 200 mL of water and heated with stirring to form a paste. The paste is used to granulate the mixed powders. The wet granules are passed through a No. 8 hand screen and dried at 80xc2x0 C. The dry granules are lubricated with the 1% magnesium stearate and pressed into a tablet.
An example of the preparation of an oral solution follows.
The ingredients are combined and mixed to form a uniform solution.
The present invention further provides a kit comprising a container comprising a pharmaceutical composition of the present invention. The container is designed to prevent contamination, minimize evaporation or drying of the composition, etc. The composition may or may not be provided in a preset unit dose or usage amount. The kit may further comprise a package insert comprising printed instructions directing the use of the pharmaceutical composition for lightening the skin.
The ability of compounds of formula I to inhibit tyrosinase may be determined using any of the following procedures.
1. Tyrosinase (DOPA oxidase) Assay Using Cell Lysate:
Human melanoma cell line, SKMEL 188 (licensed from Memorial Sloan-Kettering), is used in the cell lysate assay and the screen. In the assay, compounds and L-dihydroxyphenylalanine (L-DOPA) (100 xcexcg/ml) are incubated with the cell lysates containing human tyrosinase for 8 hrs before the plates are read at 405 nm. Potency of the compounds in DOPA oxidase assay is correlated very well with that in tyrosine hydroxylase assay using 3H-tyrosine as a substrate. Most of the compounds of formula I that were tested in this assay exhibited an IC50 of less than 10 xcexcM. For example, the compound of Example 23, i.e., (xc2x1)-3-(2,4-Dihydroxyphenyl)cyclopentanone oxime, had an IC50 in this assay of about 2 xcexcm.
2. Melanin Assay in Human Primary Melanocytes:
Compounds are incubated with human primary melanocytes in the presence of xcex1-melanocyte stimulating hormone (xcex1-MSH) for 2-3 days. Cells are then lysed with sodium hydroxide and sodium dodecyl sulfate (SDS) and melanin signals are read at 405 nm. Alternatively, 14C-DOPA is added to the cells in combination with tyrosinase inhibitors and acid-insoluble 14C-melanin is quantitated by a scintillation counter. IC50""s reflect the inhibitory potency of the compounds in the new melanin synthesis that was stimulated by xcex1-MSH.
3. Tyrosine Kinase Assay (TK):
TK assays can be performed using purified tyrosine kinase domains of c-met, erb-B2, or IGF-r. A specific antibody against phosphorylated tyrosine residue is used in the assay. Colorimetric signals are generated by horse radish peroxidase, which is conjugated to the antibody.
4. Human Skin Equivalent Model:
A mixture of human melanocytes and keratinocytes is grown in an air-liquid interphase. This tissue culture forms a three dimensional structure that histologically and microscopically resembles the human skin epidermis. Test compounds are added on top of the cells to mimic topical drug application. After incubation with the compounds (10 xcexcM) for 3 days, the cells are washed extensively and lysed for DOPA oxidase assay.
5. IL-1 Assay (Interleukin-1 Assay):
An IL-1xcex1 ELISA assay (RandD system) can be used to evaluate the effect of compounds on IL-1 secretion in a human skin equivalent model. IL-1xcex1 is a pro-inflammatory cytokine and plays a role in UV-induced skin inflammation.
6. In vivo Study:
Black or dark brown guinea pigs with homogeneous skin color can be used in this study. A solution of the test compound of formula I (5% in ethanol:propylene glycol, 70:30) and the vehicle control are applied to the animals twice daily, 5 days per week for 4-8 weeks. Using this assay, depigmentation can be determined by subtracting the light reflectance of untreated skin from the light reflectance of treated skin.
The present invention is illustrated by the following examples. It will be understood, however, that the invention is not limited to the specific details of these examples. Melting points are uncorrected. Proton nuclear magnetic resonance spectra (400 MHz 1H NMR) were measured for solutions in d6-DMSO, CDCl3, or d4-MeOH, and peak positions are expressed in parts per million (ppm) downfield from tetramethylsilane (TMS). The peak shapes are denoted as follows: s, singlet; d, doublet; t, triplet; q, quartet, m, multiplet, b, broad.
The following examples are illustrative only, and are not intended to limit the scope of the present invention.